12:55 p.m. Simon Belcher lay on his front beneath a black Range Rover, breathing deeply, wanting to unsee the pile of mangled bodies a few yards in front of him. He turned his head toward his wife, Amanda, who was hiding beneath a white 4x4 to his right. “I love you,” he mouthed silently before resting his head on the pavement.

The bullet that had struck Simon a few moments earlier passed through his torso and right arm while shrapnel from an exploding gas canister had torn into his abdomen. An unexploded hand grenade lay nearby. The masked gunmen, two of them, with military webbing slung around their bony shoulders and AK-47 assault rifles in their hands, had disappeared. Inside the mall, Simon guessed.

The blood from his wounds began to pool around him until it reached his ear, forming a seal. Suddenly, the muffled noises from within the five-story building were amplified, as if he had put a glass to a wall. Over the birdsong, car alarms, and ringing of the unanswered mobile phones of the dead and wounded, Simon could now hear gunshots, explosions, and screaming.

On Saturday, Sept. 21, 2013, the Somali militant group al-Shabab carried out an assault on Kenya’s Westgate Mall in one of the worst terrorist attacks in the country’s history. A group of young gunmen stalked the halls and stores of the upscale Nairobi shopping center, and methodically murdered at least 67 people. News of the attack seized the world’s attention, dominating international media coverage for days.

But much of that reporting was confused and contradictory, mirroring the litany of false and misleading statements made by Kenyan authorities. There were between 10 and 15 gunmen, the interior minister said. Two or three of them were Americans, said another cabinet minister. Together they took hostages, used heavy explosives, and pulled off a three-day siege, according to other government sources. Except none of these things were true.

Far from a dramatic three-day standoff, the assault on the Westgate Mall lasted only a few hours, almost all of it taking place before Kenyan security forces even entered the building. When they finally did, it was only to shoot at one another before going on an armed looting spree that resulted in the collapse of the rear of the building, destroyed with a rocket-propelled grenade. And there were only four gunmen, all of whom were buried in the rubble, along with much of the forensic evidence.

During the roughly three-and-a-half hours that the killers were loose in the mall, there was virtually no organized government response. But while Kenyan officials prevaricated, an unlikely coalition of licensed civilian gun owners and brave, resourceful individual police officers took it upon themselves to mount a rescue effort. Pieced together over 10 months from more than three dozen interviews with survivors, first responders, security officers, and investigators, the following account brings their story to life for the first time since the horrific terrorist attack occurred exactly two years ago.

9:00 a.m. The morning of Saturday, Sept. 21, was warm with a startlingly clear sky. Arnold Mwaighacho squeezed into a 12-seat minibus taxi for the half-hour commute from his home in the ramshackle town of Uthiru, on the outskirts of Nairobi, to his workplace in the city’s upmarket Westlands neighborhood. The flow of traffic was leisurely along the new multilane highway that skirted the sprawl of slums, connecting the city’s outlying workforce to its central commercial hubs.

After exiting the minibus, Arnold walked the last few hundred yards along the pavement toward the imposing sand-yellow edifice of the Westgate Mall. The 22-year-old had been working as a waiter at Urban Gourmet Burgers since it opened earlier that year on the mall’s ground floor. Even after five months, the swankiest shopping center in the city had lost none of its capacity to impress. Not that Arnold could afford to, but it was possible to blow a small fortune on Nike trainers and Adidas tracksuits, iPhones and Samsung tablets, jewelry and watches, and designer clothes, both imported and local — all without leaving the confines of the building. Besides the burger joint where Arnold worked, there was a casino, a multiplex cinema, sushi and teppanyaki restaurants, a ceviche and tapas bar, and a café selling home-baked almond croissants and fresh-brewed Kenyan coffee.

Young, confident, and good-looking, the Urban Burgers employees were mirror images of the clientele the restaurant hoped to attract. There was a calculated trendiness about the place. Waiters wore jeans and black T-shirts. The menu was written on a wall-to-wall blackboard above the brushed metal and black matte counter. Spotlights hung from a section of scaffolding, and the sound system played the latest R&B-inflected pop. The décor was industrial, and the paintwork was done by a star of the local graffiti scene. It wasn’t cheap — burgers sold for between $8 and $9 — but it was popular with a mix of foreign tourists, expats, well-to-do Kenyans, and teenaged mallrats. Arnold liked the place: The people were good; the tips were good; it was all good.

Arriving at 9:00 a.m., Arnold joined colleagues who had become friends to prep the restaurant for the busiest day of the week. The first customers stepped through the glass door into Urban Burgers almost as soon as it opened at noon. The choice tables were on the terrace outside, a perfect people-watching spot next to the mall’s main entrance. Within 20 minutes, there were four groups of customers outside ordering drinks and burgers.

Inside the mall at the Dormans coffee kiosk, Michael Kariuki rushed from table to table hustling for tips. He had landed his job as a barista and waiter just three weeks earlier. Nestled in the atrium on the ground floor, Dormans was in a prime location for catching shoppers as they walked from the mall’s main entrance toward the popular Nakumatt supermarket. Michael had arrived late for the morning shift, getting in just before 7:00 a.m. No matter: It was an unusually slow start that Saturday morning, and the 25-year-old settled in to help clean up the espresso machine and set tables for the day.

By noon, business had picked up. Michael was nearing the end of his shift, and he was keen to leave on time so that he could meet up with some friends to watch the “Safari Sevens” international rugby tournament that afternoon.

Outside, taxis dropped shoppers off at the main pedestrian entrance on Mwanzi Road, where a flight of steps ran between Urban Burgers and the Tapas Ceviche Bar up toward two sets of double-height glass doors and, beyond them, the mall’s soaring atrium. A little further down the road was the vehicle entrance. At the security barrier outside, car trunks and doors snapped open, and cars were given cursory inspections before passing the automatic security booms on their way to underground or rooftop parking lots. There were fewer spaces than usual on the roof that Saturday because of a children’s cookery competition that had set up along one side of the parking lot with tents, tables, gas hobs, and a small crowd of children and parents.

A lime-green Mercedes pulled into the right-hand lane, where it stopped before the barrier with Ben Mulwa, a 32-year-old businessman, in the passenger seat. His friend, the driver, popped open the trunk for the security check.

Inside on the 2nd floor of the mall, Katherine Walton, a 38-year-old American, had finished an early lunch of pizza and fried chicken in the food court with her five children, aged between 13 months and 14. She had given her two oldest kids, Blaise and Ian, some cash and sent them down to Nakumatt to pick up a few groceries. Nakumatt is Kenya’s answer to Wal-Mart. Its flagship outlet, spread over two levels at the back of the Westgate Mall, brought in more than $60 million a year in sales of everything from groceries and alcohol to sofa sets and children’s toys. As was usual for a Saturday morning, it was heaving with customers.

Fred Aluhondo, an electrical technician working in Nakumatt’s lighting concession, had arrived before 8:00 a.m. The 36-year-old’s work that morning was complicated by a series of power cuts that came more frequently and lasted longer than normal. He began to wonder whether there was a problem with the store’s backup generator. When he heard a muffled bang just before 12:30 p.m., Fred assumed his fears had been realized: The generator must have blown.

12:25 p.m. A silver Mitsubishi Lancer cruised along Mwanzi Road. When it stopped close to the mall’s main entrance, four men got out, their faces wrapped in black scarves, shoulder bags and ammo pouches slung around their bodies, and assault rifles in their hands. They threw two hand grenades onto the terraces along the front of the mall and started shooting.

Arnold was attending to customers on the terrace of the burger restaurant, leaning against the railing with his back to the road. He turned toward the noise as the second grenade exploded close by. He felt something hit him hard in the chest and head, knocking him flat on the ground. Just before he blacked out, he heard someone shout, “Allahu akbar!”

Standing nearby, Irene Mwelu, another waitress, felt something whizz past her head and then heard a crack as the glass door behind her shattered. She scrambled inside.

The blast that knocked Arnold to the floor did not reach Faith Muiva, who was also stationed on the restaurant’s terrace. She glimpsed two men with masked faces strafing the mall with their AK-47s before she bolted inside. Almost at once, Faith crashed to the ground clutching her leg, where she had been shot.

Kennedy Mungai, a slight 21-year-old barista who was manning the counter, saw Irene race in from the terrace and Faith tumble after her. At the restaurant’s entrance, more people were falling over one another as they surged into the mall’s atrium. Irene and another girl, Ruth Macharia, rushed to join them while Faith, bleeding, dragged herself across the floor toward Kennedy. They hid behind the counter and waited.

The four gunmen moved quickly, splitting into pairs. One pair made for the main pedestrian entrance, while the other continued along the front of the building toward the vehicle entrance.

In the queue of cars waiting to enter the car park, Ben realized his lime-green Mercedes was boxed in, with the barrier in front and more cars behind. The shooting was getting louder, closer. He leapt from the car and made for a flowerbed by a low wall to his left. Two gunmen appeared. One fired a burst of shots into the security cubicle, killing the guard inside and then turning toward Ben and another guard, who was crouched slightly in front of him. The man fired. The first bullet hit the guard in the head, spinning him onto the concrete and splashing Ben with blood. The second shot struck the ground, splintering shards of stone into Ben’s knee. He fell over and lay still, praying.

The two gunmen didn’t stop to check who was dead. They fired as they walked, hitting people in their vehicles driving out of the basement car park. They continued up the ramp toward the rooftop.

The initial explosions and gunfire triggered pandemonium inside the mall. Sandeep Wadhwa, a 46-year-old fruit and vegetable supplier who provided food for the rooftop cookery competition, had stepped into the elevator on the ground floor a moment before the attack began. The glass doors slid closed on a mundane cacophony of voices and piped music. They opened again on the second floor to the sound of shooting and screams.

Looking over the balustrade and down into the atrium, Sandeep saw people running. He dropped his shopping and joined others rushing for the exit. “Move out! Move out! We’re under attack!” he shouted as he raced for the door. Sandeep made straight for the children’s cookery competition, shouting at people to run. One of the organizers told him to calm down, saying it was probably just a robbery and would be over soon. “You fucking shit!” Sandeep shouted back. “This is a bloody terrorist attack! Switch off the gas burners, we’re under attack.”

Simon and Amanda Belcher had arrived at the rooftop parking lot a few minutes earlier. They were at a security checkpoint at the upper pedestrian entrance when a panicked mass of people forced them back. There were more explosions and rapid gunfire. This is no robbery, Amanda thought. She turned to Simon: “We need to get the fuck out of here.” Hand-in-hand, they ran toward the edge of the car park and leaned over the parapet wall to see if there was a clear way out. Instead, they saw two men with guns and black scarves obscuring their faces striding up the ramp. One of them pointed at Simon and Amanda.

The couple ran as far as they could, to the furthest corner of the car park, and threw themselves underneath a pair of SUVs that were parked next to each other.

Seeing the gunmen reach the upper car park, Sandeep, too, realized it was too late to do anything but hide. He lay on the ground inside one of the cooking gazebos with his head beneath a tablecloth. Whatever was going to happen next, he didn’t want to see it.

The gunmen stalked across the upper car park, heading for the mall’s entrance. Then they stopped, turning toward the tents that were set up for the cookery competition and the dozens of people, many of them women and children, huddled in the corner nearby. One tossed a hand grenade in their direction, then ducked behind a car. There was a deafening explosion and, in the ear-ringing silence that followed, the cries of injured children, their parents, and grandparents. The grenade spat shrapnel through the body of the man lying next to Sandeep, who felt something like a punch hit his own lower back. Reaching around, he found blood on his fingers. He played dead as the gunmen moved closer. A second hand grenade flung toward the knot of people did not explode.

The shooting on the rooftop was deliberate. Bullets were not sprayed. They were placed: bang… bang… bang. Then a pause. Then a voice: “In the name of Allah, the Most Gracious, the Most Merciful. We’ve come to kill you Christians and Kenyans for what you are doing in Somalia."

The story of the Westgate Mall attack begins in Somalia, Kenya’s neighbor to the northeast, which has been embroiled in an anarchic civil war for more than two decades. In 1991, a coalition of clan warlords overthrew dictator Siad Barre. Soon afterward, conflict and drought provoked a famine that in turn triggered a U.S.-backed U.N. aid and peacekeeping mission. It turned into a disastrous manhunt as American Marines tracked down Gen. Mohammed Farah Aideed, a notorious militia leader accused of killing peacekeepers and stealing aid. On Oct. 3, 1993, two U.S. helicopters were shot down and 18 U.S. soldiers were killed in what Somalis call the Battle of Mogadishu and which is depicted in Mark Bowden's 1999 book, Black Hawk Down, and the 2001 film of the same name.

By 1995, the United States and the United Nations had withdrawn, Aideed had won, and, for the next decade, the warlords ruled.

Militant Islam in Somalia dates back to at least the 1980s, but it came of age in 2006, when a grassroots movement called the Islamic Courts Union took control of the country, ousting the warlords. After years of conflict, hunger, and violent death, Somalis welcomed the ICU. But in the post-9/11 world, Washington did not. Fearing another Taliban, the United States encouraged and supported an invasion by neighboring Ethiopia, and in late 2006 East Africa’s most powerful military rolled across Somalia from the west all the way to the capital, Mogadishu, on the Indian Ocean. The ICU was shattered, but one of its most radical factions, known as al-Shabab, transformed itself into an Islamic nationalist insurgency, fighting first the Ethiopians and then the African Union force that replaced them.

Al-Shabab leader Ahmed Abdi Godane, who took over in 2008, moved the group closer to al Qaeda, attracting foreign jihadis and deploying suicide bombers for the first time in Somalia’s history. Godane’s vision was internationalist. In 2010, he sent suicide bombers to Uganda, where they killed 74 people in coordinated attacks on a restaurant and a rugby club where people were watching the soccer World Cup.

Al-Shabab reached its zenith that year, controlling most of southern Somalia and much of the capital. The transitional Somali government was besieged, relying entirely on foreign troops for its control of just a few blocks of Mogadishu. Mortars would land regularly in the hilltop government compound; improvised explosive devices killed government officials and passersby; gun battles were daily and deadly, kidnappings commonplace. Mogadishu earned its reputation as the most dangerous city on earth. In a harbinger of the Islamic State’s ambitions, al-Shabab administered territory, provided services, and levied taxes — none of which the Western-backed Somali government could manage.

In 2011, Kenya sent troops into Somalia to create a buffer zone between the two countries after a series of kidnappings of aid workers and tourists that Nairobi blamed on al-Shabab. The threat of retaliation against Kenya’s “foreign crusaders” was almost immediate, and the blowback has since grown in scale and ambition. At first, al-Shabab sympathizers dropped grenades at down-at-heel bars or bus stops, injuring handfuls of people. Then came bigger, more complex IED attacks and foiled plots to bomb tourist hotels on the Kenyan coast. For many Kenyans, it was a question of when — not if — there would be a big attack on one of Nairobi’s malls, which stand as symbols of the country’s secular vision for a consumerist middle-class future — the very antithesis of an Islamic jihadi worldview.

When the assault on the Westgate Mall happened, it was shocking — but not surprising. Kenyan, U.S., British, and Israeli intelligence all missed any signs of the plan, which involved just a small number of people. All it took was four young men with a willingness to die, four assault rifles, and a handful of grenades: low-tech, low-cost, low-profile, and hard to stop.

Even now, little is known about the four Westgate gunmen. The only one so far conclusively identified was 23-year-old Hassan Abdi Dhuhulow, born in Somalia and brought up as a refugee in Norway. Norwegian security forces confirmed his identity only this month, scotching rumors that he may have escaped the mall. The other three were also believed to be young Somalis: Ahmed Hassan Abukar, Mohammed Abdinur Said, and Yahya Ahmed Osman grew up in a country that existed in name only, wracked by war and routine violence, where al-Shabab offered an alternative to the venality of warlords and predations of foreign armies.

12:40 p.m. Standing in the corner of the rooftop car park, Ahmed Hassan Abukar, a.k.a. Khattab al-Kene, surveyed the dead, the wounded, and the terrified. “If there is any Muslim here, they can go,” he said. “I can see you have women and children.”

“Yes! We have children,” answered Kamal Kaur, a radio DJ and an organizer of the cookery competition, who was crouched on the ground with her young son and daughter.

“You did not spare our women and children. Why should we spare yours?” Kene answered. Then he and his partner, Mohammed Abdinur Said, a.k.a. Umayr al-Mogadish, opened fire.

Lying just inches from the killers’ feet, Amanda Belcher was surprised at how clear, steady, and confident Kene’s voice sounded. Not like a fanatic at all. No different, she thought, than if he were a greeter welcoming shoppers to the mall.

The two shooters opened fire again. A bullet grazed the head of Seema Manji, the wife of another radio DJ called Aleem, who was also struck by shrapnel. Blood poured from Seema’s wound onto her baby daughter, whom she cradled in her arms.

Aleem knew that if he did not act now he would not get another chance. He stood up, his left eye bloodied and swollen shut, and approached the gunmen as he recited the Shahada, the Islamic creed, which he knew despite being Hindu: “There is no god but God and Mohammed is His prophet,” Aleem said in English.

“Are you Muslim?” asked one of the gunmen.

“Yes, yes I am,” said Aleem.

“Is this your woman?”

“Yes, she is.”

“Ask her to cover up,” he said. Then pointing with the barrel of his gun, he said, “Leave.” And they did, clutching one another and scurrying toward the exit ramp.

Elaine Dang, a 26-year-old American who was a judge in the cookery competition, was surprised. She was too far away to hear what Aleem had said, but he was a friend and she knew that he was Hindu. She thought, “If he’s walking away, then I have hope.”

Another woman stood up, raising her hand. She also asked to leave. The gunmen asked her a question about the Islamic faith. When she failed to answer correctly, one shot her dead. Another man stood, begging for the women and children to be spared. He, too, was shot. Elaine kept her head down, using her yoga breathing exercises to stay calm, wondering how she would get out of this alive.

The shooting started up again, and hiding beneath the car, Simon was hit. Sandeep tried to crawl to safety as bullets skimmed over his head. One of the shots broke a gas pipe and set the propane alight, scorching his right arm. He stifled a cry of pain. Another volley of bullets hit a cooking gas cylinder, which exploded. Even the gunmen seemed surprised by the blast, and Elaine used the distraction to scurry under a table. She was bleeding from a shrapnel wound to her right thigh, and a chunk of her right arm, just below the elbow, was missing.

Still bleeding beneath the car, Simon watched in horror as a couple and their child tried to run and all three were shot down, crumpling to the ground in front of him. There was more shooting as the gunmen moved around the rooftop, picking out targets and firing.

Then suddenly it stopped. Less than 30 minutes after they had come onto the roof, the two attackers made their way into the mall, leaving behind them bloodied corpses, empty bullet casings, and an eerie quiet that was soon broken by the crying and moaning of the injured and traumatized.

Minutes passed, and the gunmen did not return. Slowly, people who could move began to crawl out from their hiding places under or behind cars, or to drag themselves away from the heaped bodies in the corner.

The two other gunmen, Hassan Abdi Dhuhulow, a.k.a. Abu Baara al-Sudani, and Yahya Ahmed Osman, a.k.a. Omar Abdul Rahim Nabhan, were unleashing similar carnage inside the mall after walking in through the main entrance on Mwanzi Road. Both men paused to reload their weapons before entering the mall. Each had fired a full 30-round magazine in just the first few minutes of the attack.

Sudani, in a loose black jacket and white trousers, fired through the open door of Urban Burgers and then walked in.

Faith, Kennedy, and another colleague, Anne, were hiding behind the counter. Seeing Sudani walk in, Anne gasped, drawing the gunman’s attention. He shot, and she collapsed with a cry and a sigh on top of Faith who was hunched up out of view. Then he turned to a white couple laying on the floor clutching each other in front of the counter, where they were afforded some protection from the initial shooting on the road but none from the door where the gunmen now stood.

“Fucking Americans!” Sudani said in English. Then he shot them both with bursts of fire from his rifle. Neither was American: Australian architect Ross Langdon, 32, and his pregnant partner Elif Yavuz, a 33-year-old Dutch malaria specialist who was due to give birth two weeks later, were both hit multiple times and died. Ross’s body came to rest on top of Elif’s in a last, futile attempt to protect her.

Niall Saville, a 35-year-old British development economist, and his South Korean wife, Moon Hee Kang, were also shot repeatedly at close range and left bleeding on the floor.

Outside on the terrace, Arnold came to. His right eye was swollen shut, and he was bleeding from the chest. He heard the gunfire and saw the upturned tables, chairs, and broken glass. Two customers lay by the door, wounded and moaning. Arnold smeared blood across his face and played dead. He prayed and concentrated on the Justin Timberlake song “Mirrors,” which looped over and over again on the restaurant’s sound system.

While Sudani was in Urban Burgers, Nabhan walked to the door of Little Soles, a children’s shoe shop just opposite the burger joint. Nancy Kadesa, the 25-year-old cashier, was hiding in a small storage area behind a louvered door at the back of the shop. Her colleague lay flat on the floor by the till. There were three customers in the shop, including a white man.

Nancy peeked through the slats in the door as Nabhan, standing in the shop entrance, fired a volley of six bullets into the white man. One round smashed through the door Nancy was hiding behind, inches from her head. She slid to the floor and shut her eyes.

1:00 p.m. The mall had only five exits: the basement car park, the rooftop car park, the main pedestrian entrance, an emergency exit in the back corner (of the mall’s six emergency stairwells only one led directly to the outside), and a delivery area for the Nakumatt supermarket. The four gunmen controlled two of them, and no one inside or outside knew how many more terrorists there were. Hundreds of people had found their way to the Nakumatt service entrance, either through the store or via the nearby emergency exit, and were rushing onto the street outside.

Satpal Singh, a turbaned 38-year-old Sikh, directed terrified shoppers and diners from the upstairs food court into a large bookshop that occupied most of one side of the mall directly beneath the cinema. Others made for the Millionaires Casino, a beauty salon, and other shops on the second floor. Doors were shut and locked, and people huddled at the back of the shops, hoping they would not be seen.

Dozens of people crowded into a storeroom at the Java House coffee shop, blocking the door with a refrigerator. In the bookstore, security guards pulled down the rolling shutter, and Satpal told the 30 or so people inside to put their phones on silent. As the gunfire increased in volume and frequency, both outside in the car park and downstairs on the ground floor, the group made its way up the escalator from the bookshop to the cinema above. From there, Satpal could see into the mall through the large upper windows as Mogadish and Kene, black scarves around their heads, strode around the upper floor. They seemed as interested in gazing around the mall’s shiny interior — almost with a sense of wonder — as they were in searching for targets to shoot.

Downstairs on the ground floor, the other two terrorists were also hunting for people to kill. Faith Wambua and her two children, aged 21 months and 9, were playing dead. They had been at the main entrance when the attack started and were part of the initial surge of dozens of panicked people who tumbled into the mall. Faith scooped her toddler son, Ty, into her arms and took her daughter, Sy, by the arm. They ran toward the Dormans café in front of Nakumatt and lay down on the ground between the counter and a railing.

Michael, the waiter and barista, was on the other side of the counter. He saw a running man fall to the ground in front of him. “I’ve been shot,” the man said in surprise as Michael hauled him onto his feet. They staggered into Nakumatt together. Faith wanted to follow, but knew that with her two children she would move slowly and be a big target. She stayed where she was.

Faith could see a young woman in a black T-shirt and black jeans — the Urban Burgers uniform — crouching behind a pillar and talking on her phone. Faith’s phone started ringing. She shut off the call, switched her phone to silent, and then rang back. It was her domestic helper: “This is Faith. We are at Westgate. We’re being shot at. We’re dying,” she said. Then she ended the call.

Faith kept eye contact with the woman from Urban Burgers. It was Ruth. Faith tried to signal to her, asking, “What’s going on?” “What can you see?” Ruth signaled back with upturned palms, raised eyebrows, and an open mouth: “I don’t know.”

A man’s voice called out, “Mama! Mama!” Faith did not answer, but turned her head slightly to look. She saw light-colored trousers and a black jacket: It was the terrorist, Sudani. Faith heard him talk to Ruth for a moment and then heard two shots, deafening and heartbreaking. Ruth was flung against the pillar by the close-range fire. An empty shell casing spun out of Sudani’s rifle and skittered across the floor, coming to rest a few inches from Faith and her children.

Terrified, Faith pressed Sy and Ty to the ground. She had been praying for deliverance, but now she amended her prayer: “Jehovah, please remember us in the resurrection,” she whispered.

Just a few yards away, Katherine crouched with her three young daughters. When the shooting started, Katherine had been waiting for her two sons outside Nakumatt. In the brief moment between the first explosions and the panicked dash for safety, she had time to think, “This cannot be happening!” Katherine seized her daughters’ hands and bolted left. The first potential hiding place they came upon was a cardboard promotional stand for a new tablet computer. Katherine pushed her two older daughters inside and then crawled in herself with her youngest, Petra, in a sling. The cardboard stand provided cover, but no protection at all.

The initial chaos and pandemonium was followed by an eerie quiet, punctuated by deafening gunshots that echoed through the mall. Then came footsteps: slow, almost casual, Katherine thought.

Nabhan passed Faith and her children. He passed the body of a man, shot in the head outside Barclays bank, and turned left toward Nakumatt. His stride was nonchalant. He looked around, like the gunmen upstairs, more curious than wary. Katherine was bewildered. It seemed as if the killer was out for a stroll, casually ambling around the emptied mall. He was just yards away, but did not see them huddled in the tablet stand. Instead, he fired three rounds from the hip into prone bodies lying in the open.

Nabhan was joined by Sudani, and together they entered Nakumatt, the largest and busiest shop in the mall, with hundreds of terrified shoppers and workers cowering inside.

Michael had helped the injured man reach the rear of Nakumatt, where there was a door to the delivery area in the refrigerated section just beyond the meat counter. He laid the man down on the ground among scores of other people, some wounded, most simply terrified. The man was bleeding and thirsty, so Michael went back into the shop to get water.

He was running low between the aisles, bent over at the waist, when he felt a stab of heat and pain in his left buttock that spun him to the ground. Realizing he had been shot and that the gunmen were now inside the superstore, Michael scrambled back to his feet. But a moment later, more shots struck him. One bullet passed clean through his right arm, tearing the flesh but missing the bone. Another struck his left elbow. Michael stumbled to the back of the shop, slipping in his own blood. The gunmen didn’t give chase. Instead, they walked over to the meat counter, where many people, including 35-year-old Amber Prior and her two children, were hiding behind the refrigerated display counter.*

“I can see him, I can see him,” a young Kenyan girl whispered as one of the gunmen approached. Amber didn’t believe anyone would shoot into a mass of huddled women and children. Until they did. The shots were aimed and fired deliberately. Amber lay partly on top of her 6-year-old daughter and 4-year-old son to shield them. She felt a bullet thump into her left thigh but stayed still.

After seconds that felt endless, the shooting stopped and the footsteps moved away.

Their killing spree at the rooftop cookery competition over, Kene and Mogadish took the escalator down to the first and then the ground floor. Then they also entered Nakumatt. Kene found a man hiding beneath a statue of an elephant — the shop’s emblem — by the entrance. He barely broke pace as he passed, raising his rifle and shooting the man in the gut.

By 1:15 p.m., 45 minutes after the attack started, all four gunmen were together in the superstore. There had been no security response. The only resistance they had met was from a policeman guarding a bank on the first floor who had fired, wounding Sudani in the lower right leg, leaving him limping.

A boy lay next to Amber on the blood-slicked floor, behind the meat counter. He was wounded and whimpering, his dead mother and sister next to him. Amber squeezed his hand urging him not to cry out. “Hold my hand, close your eyes, and pretend to be dead,” she said. She sent a text message to her husband: “I’ve been shot.”

The minutes ticked by. Moans fell silent as the injured succumbed to their wounds. Then came the footsteps again. This time there was a voice too, speaking in clear English with a light Somali accent.

Security footage shows Amber Prior and her two children.

 

One of the four gunmen walks a civilian out of the Nakumatt supermarket.

“If there’s any children alive here, we’ll let them go. We won’t hurt them,” said Kene. Amber got to her feet and begged him to let her children leave.

“We are not monsters,” he replied. “We just want people to understand that they can’t come to our homes and kill us. We will do the same to them.” Then he added: “I want you to forgive us.”

Kene asked where Amber was from. “France,” she replied. He said they were only interested in Kenyans and Americans.

Kene let Amber and her two children leave. He also allowed the injured boy to be wheeled out in a shopping trolley and another wounded girl to follow behind. As they passed the snacks section, Amber’s son told Kene he was “a bad man” and should have let everyone go free. Kene gave him and his sister two Mars bars each and ushered them out of the store.

Upstairs on the first floor of Nakumatt, Fred, the electrical technician, had shepherded more than 70 people into the storeroom in the minutes after the gunfire started. Elsewhere on the upper floor, customers and shop workers hid beneath furniture or barricaded themselves into glass-walled sport and footwear concessions. Fred pushed boxes up against the double-swing door linking the shop to the storeroom, leaving just enough space so that he could peer through the small glass window. He crossed the large room, filled with shelves loaded with boxes and goods, and pulled down the sliding shutter door that led to Nakumatt’s service corridors, office, and kitchen. He slipped the padlock in place and then returned to the swing door to stand guard.

On the ground floor, the four gunmen were roaming about looking for targets. Sisters Annie Gichanga, 31, and Sharon Nderitu, 33, were hiding with dozens of others among the aisles at the back of Nakumatt. Every few minutes there were more gunshots. With each bang, Annie, who was four months pregnant, repeated Psalm 27: “The Lord is my light and salvation, whom shall I fear?” Crouching beside her, Sharon swore: “Fuck, fuck!” As they hid, the power went out, cutting the lights and music. It would flicker on again sporadically, but in between all they could hear was silence, footsteps, and gunshots.

The footsteps came close, slow and deliberate. Through the gloom, Sharon could see part of a torso, an arm, and a gun. A voice spoke softly in Swahili: “They’ve gone. It’s OK, you can come out.” There was shuffling a few yards away in the next aisle across, a volley of gunfire, and silence.

1:15 p.m. Westgate is not the kind of place a Kenyan career police officer hangs out. Cpl. Nura Ali of the Nairobi Flying Squad was following his usual routine: cruising the streets with his crew, waiting for trouble to call. After 25 years in the police force, Nura was relaxed and confident as he sat in the front passenger seat with his walky-talky in his hand, a Ceska 9mm pistol in his lap, and an AK-47 assault rifle beside him. The rifle held a 30-round clip, the pistol a 15-shot magazine, and he carried a spare in the pocket of his loose-fitting slacks. His nondescript saloon car wasn’t in great condition, so, with no emergency calls coming in, he had his driver take them to a roadside mechanic to fix a loose wheel.

Nura and his two colleagues were having an early lunch of beef stew with chapati while the mechanic worked nearby when a call came through on the radio. “All units: Shooting going on at Westgate. Robbers inside.” Nura spoke on the phone to his commanding officer, who told him to get to the mall “and do whatever is necessary to handle it.” Nura left his plate of food on the table and jumped into the car. He was excited, eager even. As the unmarked squad car sped up the road, Nura hung out the window, waving his radio and shouting at drivers to move out of the way.

News of the assault was beginning to spread via frantic phones calls, texts, and WhatsApp messages. Westgate is in the heart of a Kenyan-Indian part of the city, and the close-knit community there knew better than to rely on the authorities to send help. Instead, the call went out to the community’s own licensed gun holders, who were organized into self-appointed armed neighborhood watch units.

Harish Patel, a member of an outfit calling itself the Krisna Squad, was returning home from a morning spent volunteering at the nearby Hindu crematorium when he received a distress call: There was a robbery at the Nakumatt store in Westgate, with shooting going on. A couple of minutes later, the 43-year-old was within sight of the mall. He patted the pistol he wore on his hip and grabbed the spare magazine he kept in his car.

On the western side of town, Abdul Haji was in a business meeting at the Yaya Centre, another Nairobi shopping mall. The 38-year-old bitumen trader was sipping an Americano when his white iPhone chirruped. It was a text message from his brother: “Trapped in Westgate. Terrorist attack. Pray for me.”

Abdul abandoned the business meeting and rushed to his silver SUV in the basement. As he sped toward Westgate, swerving around cars and over sidewalks to cut through the traffic, he ran through a mental checklist: He had his gun, as always, a Ceska 9mm, but no spare magazine and no body armor.

He reached Westgate minutes after Nura and Harish.

As Nura approached the mall, he saw cars stopped on the road at wonky angles, some with their engines running, some with bullet holes in the windows, and some with bloodied bodies hanging out of doors or slumped against seats. Another body was splayed out across the stairs at the mall’s entrance. Not far away, a group of armed police stood, “like a flock of sheep, doing nothing,” Nura thought.

He dashed and crouched, ducking behind vehicles, reaching the main mall entrance at the same time as Amber emerged from within, her two children and two others in tow.

Abdul and Harish got off to a bad start. It was quickly clear to those outside the mall that this was a terrorist attack and there was little doubt that al-Shabab was responsible: The group had threatened Kenya’s capital and carried out a series of small-scale attacks in different parts of the country, and Nairobi residents knew the city’s malls with their wealth and crowds were obvious targets. When Abdul, an ethnic-Somali Kenyan who is Muslim, arrived carrying a pistol, Harish got in his face, shouting. Abdul pulled out his gun license ID and calmed Harish down.

Nura was the first to go up the ramp toward the rooftop car park, spurred on by shame at the cowardice of his police colleagues rather than the desire to be a hero. The carnage in the car park was horrifying. There was a mess of bodies in the corner, more scattered beneath the open-sided marquees, and still others poked out from beneath and between cars. Nura thought he was spearheading a rescue mission, but all he could see were bodies and blood. It looked like a slaughterhouse. Nura noticed some movement and stopped, suddenly realizing how he must appear: an ethic-Somali man in civilian clothes, clutching an AK-47. “I am the police,” he shouted in English. “I’m the good guy!”

The first Kenya Red Cross medics had followed Nura up the ramp. They began doing triage, finding the wounded among the dead and providing emergency first aid. Simon was pulled out from under the car and put in an ambulance with Amanda, who was unhurt. Hundreds of people were escaping through the mall’s downstairs emergency exit, and Elaine and Sandeep, both of whom had been at the cookery competition, joined the exodus from the rooftop through a stairwell at the corner of the building. Out on the street, journalists had begun to gather. Both Elaine and Sandeep were photographed, staggering and bloodied, from the mall.

The crowd outside Westgate was growing, but with no sign of any official or organized security response. Instead, an ad hoc volunteer rescue mission had begun to take shape, comprising a motley crew of uniformed, plainclothes, and off-duty police and licensed civilian gun holders. From the rooftop car park, they could hear shooting inside and could tell it was not coming from the mall’s upper levels. Nura led the way with Abdul and Harish and two plainclothes armed officers: two Muslims, a Hindu, and two Christians. All Kenyans.

They moved cautiously around the upper floor, checking for gunmen. It was slow, nerve-wracking work. Abdul, Harish, and Nura found groups of people hiding in every shop and behind every shut and locked door. They ushered them out to the car park, where an evacuation effort was taking shape. Dozens of people at a time were being led down the ramp, distraught and running, escorted by police to the ambulances that had begun to arrive.

Realizing that the shooting was coming from downstairs, the five men formed a vanguard and took the stairs to the first floor. Progress was slow as they moved cautiously, unsure of where the gunmen were, checking shops and banks and lavatories for hiding people. They found dozens everywhere they looked and encouraged them to hurry upstairs to the roof and out.

3:00 p.m. By the time they reached the ground level, it was mid-afternoon and they came under direct fire for the first time.

Nura was hit. A bullet entered his back an inch from his spine, then ricocheted off the pistol tucked in his waistband and tore back through his intestines. Hiding behind a pillar, Nura slumped to the ground, clutching his stomach and watching his blood pour out. He blacked out momentarily and awoke to rainfall. As his confusion lifted, Nura realized that the raindrops were bullets glancing off the floor all around him. He tried to stand and was hit twice more in his upper thigh, the bullets tearing a fist-sized hole in his right leg. Nura dragged himself out of the line of fire and into the Artcaffe restaurant. As he prayed to Allah in preparation for death, Nura felt hands helping him up and carrying him out of the restaurant into the daylight outside.

Abdul was crouched behind an ice-cream kiosk, trying to work out where the shots were coming from. He reckoned he had found a blind spot along a wall adjacent to the Nakumatt entrance, and during a lull in the shooting, he dashed toward it. With his back to the wall, he saw Katherine crouched beneath the flimsy cardboard stand, directly in the crossfire.

Since the moment the attack began, Katherine had been huddled beneath the promotional table with her three daughters and three other women. Portia, 4, lay flat and still with her hands over her ears, while Gigi, 2, balled up with her head tucked in like a tortoise retreating into its shell. Thirteen-month-old Petra dozed, sucked on her pacifier, or sipped from a 4-ounce milk bottle Katherine had with her. The mall’s music system kept on playing throughout, interspersed with the shooting.

“Where’s the SWAT team?” Katherine kept wondering as the hours ticked by. “Why isn’t somebody coming in here? They should be storming the place and getting us out.”

When somebody did come at last, it was one man with a handgun.

Abdul rushed back to tell Harish and the others to stop firing in case they hit her and to get some tear gas canisters to force the terrorists back from their firing position, just inside Nakumatt, while they attempt a rescue. As he turned back, Abdul saw one of the gunmen for the first time.

Slim and young with a black scarf covering his face, the man lowered his rifle and gestured with an outstretched left arm. “Kuja, kuja,” he said in Kenyan Swahili. (“Come, come.”) The terrorist was taunting Abdul. That pissed him off: There were dead people everywhere, and other lives, including his own, were at risk, and here was this young killer acting like it was all a joke. But before Abdul could shoot, the terrorist disappeared from view.

Determined to get Katherine out of the crossfire, Abdul sprinted from the pillar to a pharmacy close to Nakumatt and barged in through the glass door. As in every other shop, there was a huddle of frightened people at the back. From the door to the pharmacy, Abdul and Katherine were just a few quick strides apart. He mouthed to her his plan: He would toss a tear gas canister toward the Nakumatt entrance, and then she must run to him.

“I can’t. I’ve got three babies with me,” she said.

There was a burst of gunfire, an explosion of tear gas, and everyone bolted. First came one of the women hiding with Katherine, clutching 13-month-old Petra. Then it was 4-year-old Portia’s turn. The image of the little girl running toward Abdul was captured by Reuters photographer Goran Tomasevic, who had entered the mall. Katherine, with 2-year-old Gigi, was the last to go. Once safely inside the pharmacy, mother and daughters were ushered along the wall to the ATM machines, where there was an emergency exit. It was just before 4:00 p.m., and they were out. Later, they were reunited with Blaise and Ian, who had escaped through the Nakumatt service exit.

Abdul circled back around the atrium toward the front of the building. He was on edge. Thirsty and exhausted, his eyes were stinging from the tear gas. Thinking he might find some water to drink and to wash his face, Abdul stepped inside the Urban Burgers restaurant. It was like the rooftop all over again: blood and bodies everywhere. Abdul saw a glass of water on the counter and drained it. Then he splashed water from the sink on his face. He gazed in disbelief at the charnel house the restaurant had become and then noticed someone looking back at him. Niall, the British development economist, was badly wounded but alive. His wife, Moon Hee, had bled to death beside him in the hours after Sudani sprayed the restaurant with bullets.

Outside the mall, Red Cross workers and uniformed officers were too afraid to enter, so Abdul walked out and beckoned them in. Once they started lifting out the wounded, more appeared. Hearing Swahili voices and no gunfire, Faith Muiva, who had hidden next to her dead friend Anne, and Arnold, playing dead on the terrace, both got up and staggered forward.

In the rear of Nakumatt, on the store’s second level, Fred worked with other colleagues to safely evacuate the scores of shoppers sheltering in the storeroom. They, too, fled around the side of the mall from the service entrance.

Nancy, the shoe-shop sales assistant, had climbed into the crawl space above Little Soles. She lay there for hours waiting to be rescued, listening to the labored breathing of her wounded colleague and customers below. She wanted to help, but was too scared to move. After an hour or so, the breathing grew fainter and then stopped. It wasn’t until around 4:00 p.m. that Nancy found the courage to leave the shop, climbing down from the roof and trying not to look as she stepped over the bodies and dashed for the exit.

Faith Wambua had not moved for hours, and her limbs had gone numb. She lay with her left arm across her son, Ty, while her daughter, Sy, pressed in beside her. To keep her children — and herself — calm, Faith sang the resurrection hymn “He Will Call” under her breath and prayed quietly. Ty lay so still that at one point Faith thought perhaps he had been hit by a stray bullet and died. The first sign of help came when Faith heard clicking and lifted her head to see a photographer taking her picture from the upper balcony. Later, at close to 5:00 p.m., she heard somebody crawling toward her. “I’m with the police,” he whispered. “You’re okay. You’re safe.”

By late Saturday afternoon, all four gunmen were holed up in a storeroom at the back of Nakumatt. They never came out again. Most of the at least 67 people who were killed at Westgate died in the first hour of the attack, before any rescue effort had even begun. Kenyan security forces did not launch their operation until 4:00 p.m., by which time it was already too late: Most of those who would escape had already escaped; most of those who would be wounded had already been struck; and most of those who would die were already dead. It is likely that many of the victims bled to death in the slow hours between the start of the attack and the arrival of help.

A special police unit trained in counterterrorism operations, known as the Recce Squad, eventually entered from the rooftop car park. Kenyan soldiers entered from the ground floor. Neither group was in communication with the other. Soon afterwards, there was a shootout on the first floor between the Recce Squad and the soldiers, in which the police unit’s commander was killed and another two officers were wounded. The remaining Recce Squad members pulled out of the operation in disgust, and the army, too, withdrew.

After the friendly fire incident, Westgate became a military operation. Armored personnel carriers with heavy machine guns patrolled in front of the mall; soldiers with rifles and rocket-propelled grenades moved in and out; and sporadic gunfire and explosions echoed from within. On Sunday, Kenya’s interior minister claimed that there were as many as 15 attackers and that the siege was ongoing. By that time, however, the mall was mostly under the army’s control. On Monday, a rocket fired by the Kenyan army collapsed the back of the mall, dropping the rooftop car park into the basement, pancaking the room where the terrorists had taken shelter and throwing a thick plume of smoke into the Nairobi sky. The fire burned for days. Parked cars with full fuel tanks fell into the gaping hole and exploded like bombs.

The heat, toxins, and structural instability of the building kept FBI agents brought in to run the forensic investigation from gathering any evidence for weeks. When they finally set to work, what they found were the charred remains of three bodies, alongside parts of three assault rifles, in roughly the location where the storeroom had been — and far from any other human remains. The fourth gunman is also believed to have died in the fire. The fragments of spine and jaw recovered by the FBI were so burned, and at such high temperatures, that neither teeth nor DNA would have likely offered much clue to the assailants’ identities.

Before and after blowing up the mall, the Kenyan army looted shops, broke open safes, and emptied tills. The looting was captured on closed-circuit television cameras and reported by business owners after they returned to the mall and found their shops ransacked and stock missing. A public inquiry into the disastrously ineffective security response was promised but never delivered. Somehow, Kenya’s interior minister managed to cling to his job for another 15 months. The army chief retired this spring, with full honors. Westgate reopened in July, nearly 22 months after the attack. Kenyan soldiers are still in Somalia, but they are now part of the multinational African Union force that protects the Somali government and fights al-Shabab, which still controls some parts of the countryside.

In April of this year, al-Shabab gunmen launched an attack in Garissa, in Kenya’s northeast, that was strikingly similar to Westgate. Four armed men broke into a university campus and rounded up students in a dormitory. After letting the Muslims go, they executed the others. One hundred and forty-eight people died that day, almost all of them young students. It was al-Shabab’s deadliest ever attack. For Kenya, Westgate was just the beginning.

Tristan McConnell is a foreign correspondent in Nairobi, Kenya. Follow him on Twitter: @t_mcconnell

Editor's Note: The time stamps in this piece represent the author's best estimate of when events occurred, based on witness interviews that were sometimes contradictory. They should be considered a rough temporal guide, not an authoritative chronology. To that end, according to witness accounts the gunmen spoke a mixture of languages: Swahili and English when speaking to civilians in the mall; Arabic when reciting scripture; and a handful of victims recall a mix of Somali and Swahili when the attackers spoke to one another. It should also be noted that the interview with Amber Prior was conducted by journalist Zoe Flood.

Correction, Sept. 21, 2015: The 18 U.S. soldiers who were killed in the Battle of Mogadishu were Army Rangers and special operations troops. A previous version of this article said that they were Marines.