A Union Pacific freight train carrying more than 60 cars, some loaded with hazardous substances, derailed on Friday in a desert town north of Los Angeles, prompting evacuations of nearby homes, fire officials said.
However, there was no sign of fire, and no injury or damage to surrounding buildings was reported.
About 30 of the train's 63 cars left the tracks, many of them overturning, at 1:25 p.m. local time in the rural community of Littlerock, Los Angeles County Fire Department Inspector Matt Levesque said.
Littlerock is about 35 miles northeast of Los Angeles.
Roughly half the cars that derailed were hazardous materials tankers, but their exact contents were not immediately known, he said, adding that Union Pacific was asked to provide fire officials with a cargo list.
Overhead footage of the scene broadcast by Los Angeles television station KCAL-TV showed numerous train cars strewn along both sides of the tracks, several of the cars lying on their sides.
Levesque said about 60 fire department personnel, including two hazmat teams, were dispatched to the scene and were examining each of the tanker cars individually for signs of possible leaks.
"It's a static situation, where they're taking their time to make sure they've investigated everything properly," Levesque told Reuters by telephone.
He said a number of homes near the derailment were being evacuated as a precaution.
The cause of the crash was still under investigation as of mid-afternoon, officials said.