GLENDALE, Calif. – A suicidal man parked his SUV on the railroad tracks and set off a crash of two commuter trains yesterday that hurled passengers down the aisles and turned rail cars into smoking, twisted heaps of steel, authorities said. At least 10 people were killed and more than 180 injured.

The SUV’s driver got out at the last moment and survived.

The collision took place just before daybreak on the outskirts of Los Angeles. Employees at a Costco store rushed to the scene and pulled riders from the tipped-over double-deck cars before the flames reached them. Dazed passengers staggered from the wreckage, some limping. One elderly man on the train was covered in blood and soot, his legs and arms apparently broken.

“I heard a noise. It got louder and louder,” said passenger Diane Brady, 56. “And next thing I knew, the train tilted, everyone was screaming, and I held onto a pole for dear life. I held on for what seemed like a week and a half. It was a complete nightmare.”

Dozens of the injured were in critical condition, and more than 120 people were sent to hospitals.

The wreck set in motion a huge rescue operation involving more than 300 firefighters, some of whom climbed ladders to reach the windows of the battered train cars. A triage center was set up in a parking lot, where the injured lay sprawled on color-colded mats – red for those with severe injuries, green for those less seriously hurt.

It was the nation’s deadliest train accident in nearly six years.

Authorities said Juan Manuel Alvarez, 25, of Compton, parked his sport utility vehicle on the tracks and got out before a Metrolink train smashed into it. The train then derailed and collided with another train going in the opposite direction. That train also jumped the tracks.

Mr. Alvarez was arrested and will face homicide charges, Police Chief Randy Adams said. Mr. Alvarez had also slashed his wrists and stabbed himself, but the injuries were not believed to be life-threatening, authorities said. Chief Adams said Mr. Alvarez had a criminal record that involved drugs.

“This whole incident was started by a deranged individual that was suicidal,” Chief Adams said. “I think his intent at that time was to take his own life but changed his mind prior to the train actually striking this vehicle.”

Mr. Alvarez’s sister-in-law, Maricela Amaya, told Telemundo TV that he had separated from his wife, Carmelita, three months ago. She said the wife got a court order to keep him away, but he had tried to see his wife and son.

“He was having problems with drugs and all that and was violent and because of that he separated from her,” Ms. Amaya said in Spanish. “A few other times he went around as if he wanted to kill himself. I said if you’re going to kill yourself, go kill yourself far away. Don’t come by here telling that to my sister.”

She said he had also threatened suicide in front of his son.

The crash occurred at about 6 a.m. in an industrial area of Glendale, a suburb north of Los Angeles. One train was headed for Los Angeles’s Union Station from Moorpark, a western suburb. The other train was outbound from Union Station to the San Fernando Valley.

About a dozen employees from the Costco ended up playing an important part in the rescue after hearing the thunderous collision.

It was the worst U.S. rail tragedy since March 15, 1999, when an Amtrak train hit a truck and derailed near Bourbonnais, Ill., killing 11 people and injuring more than 100.