Arnie Peterson's evening train, the Metrolink 111, banked to the left, toward the coast. The work week, and the metropolis, faded behind him.
He and his fellow travelers were a motley crew: a lawyer with tasseled loafers; a young man with a shaved head and the words "KICK ASS" emblazoned on his shirt; Peterson, a 47-year-old cement worker for the city of Burbank, clad in his orange work shirt, headed home to Simi Valley after another long day.
Normally, they would probably never be in the same room, but 10 times a week -- once in the morning, once in the evening, five days a week -- they were together.
Theirs was an odd kinship. Many of them had communicated for years with little more than nods, yet they were so respectful that they wouldn't think of stealing one another's favorite seats, so trusting that when they had to use the restroom, they would leave cellphones and briefcases on their seats without second thought.
Peterson was staring out the window, "thinking," he said, "about how it was Friday."
The terror, for some, began before impact. The left turn in the tracks, just above the Northridge-Chatsworth station, is very sharp. So commuters sitting by the windows on the left side could see the Union Pacific freight train headed straight for them.
"My first thought was: I'm not seeing this," said Albert Cox, 53, a regular rider who had boarded the train in Burbank and was on his way home to Simi Valley.
It was clear they could not stop soon enough. There was time for a few muffled screams before they hit.
Peterson found himself flying through the air, over six rows of seats. He is not, he pointed out, a small man.
Everything and everyone, for a moment, seemed airborne. Some of the tables, torn from their moorings, turned into missiles, hurtling toward the front of the train.
Cox was thrown from his seat -- there are no seat belts, since Metrolink trains are not designed for sudden stops -- and landed on a table, breaking it in two. "The table won," he said. Peterson was thrown, with 20 others, against one wall of the train.
Suddenly, but for black oil seeping from the freight train and black smoke billowing from the impact site, everything stopped moving.
"It was dead quiet," Peterson said.
Slowly, the sound built again -- moaning, then screaming. Phil Thiele, 55, of Simi Valley, who had boarded the train at Van Nuys, had been sitting in the back of the first passenger car. Now he looked up into the face of a man who was pinned between collapsed seats.
"He was pleading with me to help him," Thiele said. "I tried my damnedest to get him out but I just couldn't."
Nearby, a woman with a serious head injury was trying to crawl through the wreckage. Thiele had received first-aid training this week at work; he urged the woman to stay put and placed her purse under her head as a pillow.
Across the train car, through the darkness, a scream: the fire was spreading. Thiele turned back to the pinned man. "Don't worry," he told him. "I'll stay with you as long as I can."
Soon, the first firefighter peered inside. Help was heading toward the wreckage from every direction now, through the back of a residential cul-de-sac, running down bridle paths used by local families that board horses. The passengers who could move on their own were clawing their way to safety.
"People were climbing out of the side, bleeding, crying, screaming," said Katharina Feldman, who was working out of her nearby home office and raced to the scene with bottles of water after calling 911. "It was like a war zone."
Firefighters assigned her to a man whose head was gashed. The man asked her to call his wife; she did, while holding his IV.
Around them, the wounded came spilling out like ants in a rainstorm. Feldman spoke with a dazed woman in her 70s; she had broken her teeth and was having chest pains. Arnie Peterson was sitting on the ground, leaning against a fence. He had blood caked on his left arm; he wasn't sure, he said, if it was his or someone else's. One woman was carried out, her femur clearly snapped in two.
The injured were laid out in a triage area near the school. Those with moderate injuries were led to a large green tarp, those with serious injuries to a yellow tarp, and those in the worst shape to a red tarp.
Some victims had their whole heads wrapped in gauze. One man was sitting on a lawn chair; a Barack Obama button was still affixed to his white T-shirt, which was drenched in blood. Helicopters used a nearby soccer field where children had been practicing an hour earlier.
Long after the sun set, family members pressed against police cordons, desperate for information.
At one command post, Frank Haverstock was waiting, frustrated and anxious, behind police tape. Haverstock, 64, of Simi Valley, said his wife, Norma, 53, the manager of a custom drapery house in Burbank, was a regular commuter on the train.
After the collision, he said, she had called him. She told him that she was bleeding from the head, that she "hurt all over."