By ADAM NAGOURNEY, JENNIFER MEDINA, IAN LOVETT and JULIE TURKEWITZ

New York Times

SAN BERNARDINO, Calif. >> The noise was deafening. The blast of gunshots. The piercing shriek of a fire alarm, and the torrent of water gushing from the sprinkler system, mixing with the blood on the floor.

But what the people who were there remember most about Wednesday — the county workers hiding behind a coffee cart, the police officers who arrived four minutes after the first 911 calls at 11 a.m. — were the heart-wrenching screams and moans, the chaos and sense of utter panic.

As people lay dying on the floor, the attackers, wearing masks and dressed in black, were firing from rifles held at waist level, shooting methodically at anyone who still seemed to be alive.

“Everyone started running,” said Christian Nwadike, 62, a health inspector who hid in a bathroom as the building shook with each rifle shot. “Many made it, many did not.”

This gathering on a bright, warm, Southern California morning was supposed to be a mix of business — admittedly dreary training sessions for workers from the San Bernardino Health Department — and an early holiday celebration. The first-floor auditorium at the Inland Regional Center was decorated for Christmas, and many of the 100 people there took a moment to pose with colleagues for photographs in front of a Christmas tree.

But that ended when a colleague, Syed Rizwan Farook, 28, who had been there and quietly slipped away, leaving his jacket draped over a chair, returned with his wife, Tashfeen Malik, 29, to unleash what the FBI is calling a terrorist attack. It played out in the unlikeliest of places: a center that helps disabled people in a sprawling suburb an hour outside of Los Angeles. The health department, where Farook was an inspector, was holding its event at the center.

The attack left 14 people dead and 21 people injured. Survivors describe harrowing moments when they thought that they were about to die.

“I was just saying, ‘Please, Lord, help us,’” Regina Kuruppu, 46, said, recalling how she and three co-workers hid under a desk, grabbing one another and praying. “‘Help us, help us to get through. Heavenly Father, if it is your will, let it be your will.’ I didn’t know if we would be taken or not.”

Outside, Lt. Mike Madden of the San Bernardino Police Department was among the first to arrive on the scene, pulling in — by pure luck, as he put it, — in front of Building 3, where the attack was unfolding.

Remembering the training he had received for this kind of cataclysmic event, he waited two minutes for backup. When reinforcements arrived, he assembled an entry team that, guns drawn, went in to flush the building of what panicked survivors told him could be as many three people with guns.

“It was unspeakable the carnage that we were seeing,” Madden said. “The number of people who were injured and unfortunately already dead. And the pure panic on the faces of those individuals who were still in need.”

The fire alarm was ringing. Water was pouring down from the sprinklers. The air was filled with smoke and the smell of gunpowder; the floor was scattered with the dead and the injured; and people were crowded into corners and behind furniture.

“We went further into the building,” Madden said. “That was a difficult choice we had to make: passing people who we knew were injured and needed assistance. But our goal at that time had to be trying to locate the shooters.”

The attackers had left. Madden found 50 people crowded in the back of a hallway. Again and again, he told them to come out and leave the building. But they stayed, paralyzed with fear, until one of them tentatively began the flight to safety.

“And then,” Madden said, “the floodgates opened.”

‘Fight? Syed? No.’

The attack that took place here Wednesday morning was, in many ways, an assault on the multicultural America that is enshrined in this part of the country and was represented in this room: county workers, many of them immigrants who had found solace in this pleasant suburban community. Among them were Muslims who shared a faith with the assailants, who by every indication fired indiscriminately at the crowd, not taking into account ethnicity, religion, race or economic class. Farook knew many of them as colleagues.

These were people who had come to one of the few places in Southern California where it is possible to buy a home for less than $100,000, and to enjoy the year-round climate and soft light on the San Bernardino Mountains, which provide a scenic backdrop from almost any vantage point.

The annual event was known as a GEM, or general education meeting, called by the San Bernardino Health Department. It began at 8 a.m. with coffee and pastries, and was meant to end as the sun was setting around 4:30 p.m., after a break for a holiday lunch.

The attendees assembled in the conference room, which is designed to hold about 500 people. They settled in to applaud for the familiar events of the day: the award for the employee of the year, the discussion of goals for 2016, and this year a video presentation on how to conduct a trash inspection, one participant said. They engaged in a bonding exercise called “clicker,” using wireless clickers to answer questions on a video screen.Farook had arrived with everyone else before 8 a.m., and taken a seat at one of the tables in the back of the room, joining four other workers, including Nwadike. Farook was, to everyone who knew him from his five years working for the department, quiet and reserved, engaging conversation only when colleagues like Nwadike greeted him good morning.

“He was himself,” Nwadike said. “He was quiet. He doesn’t laugh — he smiles. He hardly initiates conversation.”

In the hours after the attack, there were some suggestions that Farook had engaged in an argument with someone at the center, though that does not appear to have been the case. He just left, without warning. “Fight? Syed? No,” Nwadike said. “I’ve never seen him disagree with anyone.”

It took a while before anyone noticed his absence, as many employees in the crowded conference room were coming and going, running to the bathroom and quickly coming back. When the clickers were handed out for the game, Farook was gone. “I asked people to leave a clicker for him,” Nwadike said.

In all, Farook was gone at least half an hour.

“He didn’t pack and leave — an indication he would be back,” Nwadike said.

A Couple in Black

The schedule called for a break at 11 a.m., and the Health Department employees pushed back from the table. Some went to the bathroom in what would turn out to be a lucky break on a dark day. Others went for coffee, or to pose in front of the Christmas tree, lit up and gleaming.

No one apparently noticed when Farook and Malik first appeared outside the door. They announced themselves with the rapid-fire barrage of bullets. People in the room froze, witnesses said, unsure what was going on, some even wondering for a second if this were some sort of surprise holiday celebration.

But as people saw the couple dressed in black — their faces covered by masks and their bodies loaded with weaponry, including two .223-caliber assault rifles and two 9-millimeter semiautomatic pistols — panic swept the room. People scattered as colleagues collapsed with anguished screams. Some reached for their phones to call 911; one person who tried to call said he was unable to get through.

No one interviewed recalled the assailants saying anything.

On the second floor, where Kuruppu was meeting with colleagues, it first sounded, she said, as if the people downstairs were moving furniture.

Then the sounds of gunshots exploded through the room, and the fire alarm went off.

Kuruppu and her colleagues immediately began to follow the procedures of a fire alarm, she said. They checked other rooms for people and headed downstairs, where they saw broken glass — and bodies.

“I thought, ‘Oh my God, what happened?’” Kuruppu said. “I was holding both hands of two co-workers. I said, ‘We need to get out of here.’” They started to run outside; a colleague, standing outside, yelled at them to stay in the building.

The four co-workers ran back to the second floor and rushed into an office, pushing cabinets in front of the door. Through a window, they could see police officers in the yard. Outside, Kuruppu heard a loud voice coming closer. “Next thing you know, the door was broken down,” she said.

It was the police.

The entire attack had lasted two to three minutes, survivors said, enough time for the couple to fire 65 to 75 rifle rounds. The couple left behind four spent high-capacity magazines and three pipe bombs as they fled in a rented black Ford Expedition with Utah plates, the sound of sirens approaching.

After Madden and the waves of emergency service officers who rushed to the scene were certain the attackers had fled, the police shouted out for everyone in the buildings to leave — and to keep their hands up. For people who had been hiding, the scene outside was gruesome. Some bodies were covered with tarps, and emergency service officers were tending to the wounded or loading them into ambulances.

About four hours later in a neighborhood less than 2 miles from the site of the massacre, Farook and Malik were killed in a gun battle with scores of police officers who had converged on their vehicle. “Suspect down,” a police officer announced over the scanner. It was 3:16 p.m.

Nwadike later said he had not given any more thought to where Farook was. And it was not until 7 p.m. — after he had returned home, one of many people evacuated by the police and questioned before being let go — that he realized why his co-worker’s chair had been empty that morning.

© 2015 The New York Times Company