Rescuers were still carefully picking apart the twisted wreckage Saturday when Metrolink announced - 19 hours after the crash - that its preliminary investigation determined the engineer failed to heed a red signal light, leading to the collision with a Union Pacific freight train.
The Metrolink engineer was among the dead, the NTSB said. His name has not been released. A total of 135 people were injured.
The NTSB, which is leading the investigation, played down a local television station report that the engineer had exchanged a brief text message with a teenager shortly before the crash. KCBS said the teen was among a group of rail fans who befriended the engineer and asked him questions about his work.
"I personally have been in accident investigations where similar reports were made that turned out to be inaccurate so I want to be very, very careful about it," NTSB member Kitty Higgins said at a news conference late Saturday.
Metrolink spokeswoman Denise Tyrrell said she would consider it "unbelievable" that an engineer would be text message while operating a train.
There was no change in the death toll Sunday. There were no new reports of any injured passengers dying at hospitals and the crash site had been cleared of bodies, said Lt. Cheryl MacWillie of the Los Angeles County coroner's office.
Tyrrell said Saturday that the company was stepping ahead of the NTSB in suggesting a cause of the accident because "we want to have an honest dialogue with our community." She said internal investigators had reviewed dispatcher recordings and operation of the trackside signal system.
Part of the railroad's safety system involves a series of signals that tell engineers whether the path ahead is clear. According to Metrolink, the engineer missed a stop signal shortly before the accident site - the last of three that would have warned another train was ahead on a single stretch of track. In that area, trains going both ways share track that winds through a series of narrow tunnels.
The NTSB did not rule out Metrolink's theory but will complete its witness interviews and review of evidence - which could take a year - before announcing conclusions.
"We don't know why it happened, and it's our job to find out," Higgins said Saturday.
Higgins said rescue teams on Saturday recovered two data recorders from the Metrolink train and one data recorder and one video recorder from the freight train. The video has pictures from forward-looking cameras and the data recorders have information on speed, braking patterns and whether the horn was used.
The passenger train was believed to have been traveling about 40 mph.
Investigators planned to test the signals on the track and the brakes on the trains as well as interview Metrolink dispatchers.
The collision occurred on a horseshoe-shaped section of track near a 500-foot-long tunnel underneath Stoney Point Park in the San Fernando Valley. There is a siding at one end of the tunnel where one train can wait for another to pass.
Higgins noted that a pair of switches that control whether a train goes onto the siding were open. One of them should have been closed, she said.
"The indication is that it was forced open," possibly by the Metrolink train, she said.
The Metrolink train, heading from downtown Los Angeles to Ventura County, was carrying 220 passengers, one engineer and a conductor, and the freight train had a crew of three.
The crash forced the Metrolink engine well back into the first passenger car, and both toppled over. Two other passenger cars remained upright.
Of the 135 people injured, 81 were taken to hospitals in serious or critical condition. No overall condition update was available Saturday, but a telephone survey of five hospitals found nine of 34 patients still critical.
The Metrolink engineer was employed by Connex Railroad, a subsidiary of Veolia Transportation, which said it began operating Metrolink routes in 2005. The company issued a brief statement saying it was "fully cooperating" with investigators.
Metrolink's assertion that engineer error caused the accident drew some criticism.
Los Angeles County Supervisor and Metrolink board member Don Knabe said it's premature to blame the engineer.
"There could always be a technical malfunction where ... there was a green light both ways," he said.
Ray Garcia, a Metrolink conductor until 2006 who now works for Amtrak, said initial evidence could be misleading, as in the case of a central computer inaccurately showing that a signal was red.
"It is a rush to judgment," he said. "It's just way too early in the game to point the finger."
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