A motor home stopped on the tracks has been hit by a commuter train and burst into flames near Los Angeles.
There were no immediate reports of major injuries following the fiery collision at around 5.30am at a rail crossing intersection in an industrial area of Santa Fe Springs.
The crash caused major delays during rush hour.
Passengers and crew on Metrolink’s OC Line 681 were safely evacuated.
Passenger Ryan Hajek said he felt the train operator slam on the brakes as it approached the crossing.
Mr Hajek told TV station KABC-TV: “The lights inside went dark, so we knew something went wrong, I knew we crushed into something. As we stopped, I saw all the debris of what looked like a car on the side of the tracks, and I knew then that we had hit something.”
Four people on board complained of pain and were treated at the scene.
Investigators will try to determine why the motor home was stopped on the tracks.
Fire crews doused the flames, which gutted the motor home and charred a rail carriage on a freight train stopped on a parallel track.
The freight train was unable to stop in time and ran over some of the crash debris, according to Lena Kent, spokeswoman for BNSF, which maintains tracks in the area.
Police were looking for four people seen running from the tracks just prior to the impact, but it was not immediately known if they were coming from the motor home.
The collision occurred at a crossing equipped with gates and flashing lights, Ms Kent said. It was not clear if the motor home tried to drive around the gates, she said.
The Metrolink train with five passenger carriages was heading north from Orange County when the crash happened about 15 miles south-east of downtown Los Angeles.
Buses were ordered to take 120 evacuated passengers to Union Station in Los Angeles. Widespread delays were expected on Metrolink’s Orange County and 91/Perris Valley lines.