The death toll of Los Angeles train collision rose to 18 overnight and more bodies are expected to be found as rescue workers pick through the wreckage of Friday's accident, officials said Saturday.
A Metrolink commuter train collided with a freight train in the Chatsworth area, about 50 kilometers northeast of downtown Los Angeles, Friday afternoon, in the deadliest accident in the 12- year history of the region's railway public transportation system.
Emergency personnel in the morning continued their intensive search for victims and the event recorders carried by the commuter train and the freight train.
The confirmed number of deaths was 18 and several dead people remained trapped in the wrecked train as of Saturday morning. And of the 135 people injured in the crash, 45 were listed as critical, 40 in serious condition and 50 had suffered minor injuries.
"We expect the confirmed death toll will continue to rise," said Metrolink spokeswoman Denise Tyrrell.
Meanwhile investigators already began to examine possible causes of the crash. The two trains were on the same track from opposite directions when they collided.
The U.S. National Transportation Safety Board, which reportedly had investigators at the scene last night, is poised to officially take over the investigation later in the day.
Authorities are also searching for the trains' event recorders, which, like the so-called black boxes carried by airlines, monitor the actions of engineers on the trains and should provide investigators with crucial information regarding how the accident could have occurred.

California Governor Arnold Schwarzenegger issued a statement Saturday calling the head-on train collision a "tragedy" and promised the state's support and cooperation for the rescue effort.
"We are working to ensure that Los Angeles County's emergency response agencies have any and all assistance they may need from the state," said the governor, who is expected to inspect the crash scene in the afternoon.
Los Angeles Mayor Antonio Villaraigosa earlier called the collision "a human tragedy that is beyond words." He said a police officer on the commuter train alerted the authorities immediately after the collision occurred.
Friday's crash is the deadliest accident in the history of Metrolink, which began to serve the Los Angeles metropolitan area in 1992. It is also believed the deadliest U.S. train crash in nearly two decades.