The death toll from a head-on collision between a passenger train and a freighter rose to 25 on Sunday with officials saying a train engineer's failure to heed a red light signal caused the catastrophic crash.

"At this moment we must acknowledge that it was a Metrolink engineer that made the error that caused on Saturday's accident," Metrolink spokeswoman, Denise Tyrell said.

The collision, which took place in Chatsworth on Friday afternoon also left more than 135 injured, 40 of them critical as rescuers continued their grueling work of extracting bodies from a tangled mountain of steel, while family members waited anxiously outside hospital rooms for their loved ones.

The crash happened when a Metrolink passenger train with 222 people aboard apparently failed to stop at a signal near, and smashed into a freight train.

The National Transportation Safety Board and other agencies are gearing up their investigations and are yet to examine the "black box" and other crash-site evidence, it reported.

Governor Arnold Schwarzenegger described the wreck as "one of the worst train accidents in modern history in California," and officials said more people are still trapped beneath the twisted metal of a double-decker train car.

According to Federal Transportation officials each train was believed to be traveling at the time of the head-on collision at about 60 kilometers per hour. The impact saw the first passenger car collapse into its locomotive. At least seven cars from the freight train derailed.

The crash was the deadliest since a Metrolink crash of January 2005, when 11 people died and dozens were injured when a Metrolink train slammed into a Jeep Cherokee parked on train track, derailed and hit a freight train.