The death toll in the head-on crash of a commuter train and a freight train outside Los Angeles has risen to 24 and more fatalities are expected, officials said on Saturday.
The Friday afternoon crash -- the worst commuter train crash in Los Angeles history -- was likely caused by the passenger train engineer's failure to stop at a red light, officials said.
"We have confirmed 24 dead and are still working to extricate bodies," said Los Angeles Fire Department spokesman Ron Myers.
The collision also injured 135 people, including 45 who were in critical condition.
"At this moment we must acknowledge that it was a Metrolink engineer that made the error that caused yesterday's accident," Denise Tyrrell, a spokeswoman for the train line, said at a news conference.
She said the engineer worked for a subcontractor used by Metrolink. The engineer was believed to have died in the crash.
There were 222 people on the Metrolink train, and three Union Pacific employees aboard the freight train, according to media reports.
Fire Department officials said workers were continuing efforts to extricate the bodies from the twisted wreckage.
The force of the crash pushed the locomotive engine pulling the commuter train backward into a passenger car, and both toppled over, igniting in flames. At least seven cars from the freight train derailed, although most remained standing across the tracks.
Both trains were travelling at about 40 miles per hour (65 kph), according to Tyrrell.
Los Angeles Mayor Antonio Villaraigosa called Friday's collision "a human tragedy that is beyond words."
Once rescue efforts conclude, the National Transportation Safety Board is poised to take over investigation of the crash.
Workers were searching for the event recorders carried by the two trains and the dispatch station recording involving the crash were to be turned over to NTSB investigators on Saturday.
The event recorders -- like the so-called black boxes carried by airliners -- monitor the actions of engineers on the trains and should provide investigators with crucial information regarding the cause of the collision, Reuters reported.