OXNARD, Calif. >> A commuter train slammed into a truck abandoned on the tracks early Tuesday, sending three rail cars tumbling onto their sides and injuring 28 people in the fiery crash in California.

The accident occurred around 5:45 a.m. about 65 miles northwest of Los Angeles. Four people had critical injuries.

The truck driver was found several miles away, and authorities were questioning him about why the vehicle was left on the tracks.

Glenn Frisbie was driving to work and sitting at an intersection about a block away when the train struck the truck.

“I saw a bright flash, a big fireball and flames, flames going pretty high,” he said.

Little was left of the truck except scorched and mangled wreckage, with some debris found in a nearby intersection and some close to the tracks.

“When the crews arrived on scene, it was in flames, the vehicle, and it was pretty much cut in half,” Oxnard Fire Battalion Chief Sergio Martinez said.

The Metrolink train carrying 48 passengers and three crew members was heading from Ventura County to Los Angeles. The injured people were taken to several hospitals.

The locomotive, which was pushing the train from the back, was upright. The stretch of track is straight and that allowed the conductor to see the truck and begin braking, Martinez said.

The train typically would be accelerating out of the Oxnard station at about 55 mph, Metrolink spokesman Scott Johnson said. With braking, he estimated it would have hit the truck at between 40 mph and 55 mph.

The crossing had arm gates, signal lights and a center median, said Francisco Castillo, a spokesman for Union Pacific Railroad, which owns the tracks.

Johnson said initial reports from the scene indicated the arms and lights were working.

None of the rail cars crumpled, and that likely explains why there weren’t more serious injuries. That’s the aim of “collision energy management technology,” which disperses energy from the impact, instead of allowing it to concentrate inside the cars, Johnson said.

Metrolink invested heavily in such technology following two other major crashes on its lines over the past decade.

Twenty-five people were killed on Sept. 12, 2008, when a Metrolink commuter train struck a Union Pacific freight train head-on in the San Fernando Valley community of Chatsworth. More than 100 people were hurt in one of the worst railroad accidents in U.S. history.

Federal investigators later concluded that the Metrolink engineer had been texting moments before the crash and ran a red light.

In 2005, 11 people were killed and about 180 were injured when a man who later claimed he was suicidal parked his SUV on tracks in suburban Glendale and fled before an oncoming Metrolink train struck it and derailed, hitting a second Metrolink train.

The National Transportation Safety Board and the Federal Railroad Administration were sending investigators to the Tuesday crash in Oxnard.

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Associated Press writers John Antczak and Justin Pritchard contributed from Los Angeles, Alina Hartounian contributed from Phoenix.