Washington - At least 15 people died and more than 100 others were injured Friday in a train accident near Los Angeles, local television channel KTLA reported, citing rescue teams.

Hours after a commuter train and a freight train crashed at 4:23 pm (2323 GMT Friday) near Chatsworth, in the San Fernando Valley north of Los Angeles, rescuers were still pulling trapped passengers from the train wreckage.

"This is the worst accident I've ever seen," Los Angeles Mayor Anthony Villaraigosa said. "Clearly the injuries are going to mount and so are the fatalities."

Police had put the death toll at 10 to 20.

At least 10 of the injured were in serious condition and the authorities feared that the number of dead might increase, the report said.

The commuter train was busy at the time, with an estimated 350 to 400 passengers. The Metrolink commuter train left Los Angeles at 3:35 pm, heading north-west. According to the operators, two drivers were manning the Union Pacific freight train bound for Los Angeles.

The causes of the accident were not immediately known. Several wagons were derailed and caught fire, while scores of passengers were trapped in the train wreckage.

Television footage of the site of the accident showed fire department personnel rescuing injured passengers from an overturned wagon. Debris from the freight train was strewn across the tracks.

Rescue helicopters flew the injured to nearby hospitals, and scores of ambulances drove to the site of the crash.

The fire department said more than 100 of their personnel were responding to the accident.