"It was the worst thing I'd ever seen," Castro said later.
Nagel was no rookie; in his 18-year career he had responded to the Northridge earthquake in 1994, to the Glendale-area crash in 2005 that was, at the time, the deadliest in Metrolink history. But what he found inside, amid the smoke and crumpled metal, was devastating. He began to make dismal calculations. Two or three could be extracted quickly. Six or seven were dead.
"About eight or 10," Nagel said, "were alive but weren't going to make it."
Barrios lives in Moorpark; many of the crash victims, he figured, lived in his community. One man screamed for help; all they could see was his hand sticking out from under another passenger's body. Others were shouting: "Get me out! Get me out!"
"You know these people were going home to their families," Barrios said. "But they're not going home."
On one level, it wasn't a complex mission. "You've got to get them out of there and you've got to get them to the hospital," Barrios said. But he knew it would be more complicated than that.
Rescuers pulled the first two victims out of the front car relatively easily, by throwing aside seats and pulling away wreckage with their hands. Saving anyone else -- even getting to anyone else -- would prove more difficult.
Only one other victim was even partly accessible, a man in his late 40s, his brown boots sticking out from the mangled seat that had trapped him. The man was able to speak, albeit softly because of the pressure on his chest. It took half an hour for rescue workers to cut through an air conditioning unit and a table to get him out, but that man was expected to survive.
It only got harder from there. At one point, the cutting tips of one crew's "jaws of life" broke as firefighters cut through sheets of high-density metal. They had to bring in special saws with diamond-tipped blades.
Not far away, officials were turning a school parking lot into an instant airport, with heliports, fuel trucks and the equivalent of an air-traffic control center.
Helicopters ferried dozens of people to hospitals as others landed with search-and-rescuers carrying "go kits" -- bags packed with lights, devices that allowed them to listen through walls for struggling victims, crowbars and hand-held jacks designed to peel apart distended metal.
The air was thick with the stench of fuel and the noise was deafening -- helicopters, trucks rumbling through the hills. Dogs scoured the cars, trying to find survivors. Rescuers hung powerful spotlights from cranes at dusk.
"It looked and sounded like it came out of a movie," said Searcy Jackson III, a firefighter who reported to the scene from Fire Station 88 in Sherman Oaks. "It didn't look real."
Rescuers went on "autopilot," said Los Angeles Police Assistant Chief Jim McDonnell. He described it as "organized chaos."
"There was so much to do in such a short time frame," McDonnell said. "The thing I'm left with is a tremendous tragedy, of course, but also an acknowledgment of the training and the relationship that exists among first responders. It was critical. And in this case it saved many lives."
They could not, of course, get to everyone in time.