LOS ANGELES, California (CNN) -- Ten people were killed and many others injured Friday when a Metrolink train packed with hundreds of rush-hour commuters collided with a freight train in suburban Los Angeles, officials said.
A commuter rail car lies on its side after a collision Friday near Los Angeles, California.
The apparent head-on collision between Metrolink train 111 and the Union Pacific train occurred about 4:30 p.m. (7:30 p.m. ET) in Chatsworth, a suburb northwest of Los Angeles. It sparked a fire that was brought under control.
Los Angeles County sheriff's spokesman Steve Whitmore said 10 people had died, as rescuers continued to search the wreckage.
An estimated 350 to 400 people were on the commuter train, which was heading north, said Metrolink spokeswoman Denise Tyrrell. Passengers were still being evacuated, she said. Three passenger cars and one locomotive were involved in the crash.
At least one car from the commuter train had derailed and was lying on its side.
Five victims -- three males and two females, all in critical condition -- were received at Providence Holy Cross Medical Center in Mission Hills, said spokeswoman Natasha Shows. More are expected, she said, as ambulances from the hospital remain at the scene.
The Associated Press reported that firefighters pulled passengers out a rear door and down a ladder from the toppled commuter car, which had been separated from the rest of the train by several feet. Crumpled and charred freight cars were strewn across the tracks, the AP said, and dazed and injured passengers sat on the ground and milled about on both sides of the tracks.
Video from the scene showed a number of injured people lying on blankets. Passersby had attempted to free some passengers from the train cars before fire and rescue crews arrived. A helicopter was on the scene, ferrying people to hospitals. Watch a report on the collision »
CNN affiliate KCAL reported about two dozen people were injured.
The AP said that one of the largest medical facilities in the area, Northridge Hospital Medical Center, was told to prepare for the arrival of injured passengers, according to hospital spokeswoman Christina Zicklin.
"We are expecting some people. I don't know the number yet," she said, according to AP.
Tyrrell said the train left Union Station in downtown Los Angeles and was headed northwest to Moorpark in Ventura County, according to AP.
"We don't know if we hit another train or another train hit us," Tyrrell said, according to AP.
The cause of the collision is unknown.
The AP said the crash happened in an area where the tracks form a "U" shape, about 2,500 feet (762 meters) wide. At the top of the bend is a 500-foot-long tunnel that runs beneath Stoney Point Park, popular with climbers for its large boulders, the AP reported.
CNN's Ted Rowlands contributed to this report.
Copyright 2008 CNN. All rights reserved.This material may not be published, broadcast, rewritten, or redistributed. Associated Press contributed to this report.
All About Train Travel • Los Angeles
Firefighters stand near a locomotive on September 12, 2008 after a Metrolink passenger liner collided with a Union Pacific freight train near Chatsworth, California.
At least 25 people have been killed and many more injured when a Metrolink commuter train collided yesterday afternoon with a Union Pacific freight train in the Chatsworth district of Los Angeles. Around 250 firefighters have responded to the accident scene. 

Estimates are that 350-400 people were on the number 111 commuter train which departed from Los Angeles' Union Station at 3:35pm PDT. The collision occurred on Friday at about 4:25pm PDT on Metrolink's Ventura County Line. The area in which the crash took place is hilly and contains a single track; it is just north of the Chatsworth Metrolink station.

The force of the collision sent the locomotive of the Metrolink train to penetrate deep into the lead bi-level passenger car of the three-car train. The collision then knocked the Union Pacific and Metrolink locomotives on their side along with the lead passenger car. 


According to various sources, upwards of 10-15 passengers, possibly even more than 20, have been killed, including a Los Angeles Police Department (LAPD) officer. The LAPD has not released the name of the officer.  The engineer of the Metrolink train is believed to be another of the fatalities.

The number of injured is believed to be 135, although the precise number is still unclear. According to emergency responders, the injured have been transported to Los Angeles area hospitals, including the University of California, Northridge Hospital Medical Center,  Providence Holy Cross Medical Center and Huntington Hospital.

“This is the worst accident I’ve ever seen. Clearly the injuries are going to mount and so are the fatalities,” Mayor of Los Angeles, Antonio Villaraigosa, said.

It is unclear how the accident occurred. Some of the possibilities include a signal malfunction, a failure by a crew member to notice a signal or a lapse in protocol for moving trains safely in the area. According to Metrolink and the Los Angeles Times, the National Transportation Safety Board has a team on scene and is investigating.

In an apparently unrelated incident less than an hour after the crash in Chatsworth, another Metrolink train collided with a car in Corona, California, killing the female driver of the automobile.