A freight train carrying hazardous materials (search) derailed in a Southern California community, forcing more than 200 people to evacuate and damaging at least four homes. No serious injuries were reported.

Nearly 50 freight cars and trailers jumped the tracks Saturday, Los Angeles County sheriff's deputy Luis Castro said. About 500 gallons of diesel fuel spilled.

Union Pacific (search) spokeswoman Kathryn Blackwell said railroad officials would survey the damage Sunday before deciding when the tracks could be returned to service. In the meantime, freight trains were being diverted to other lines.

Blackwell said the crash may have been caused by a broken rail. "It doesn't appear it was human error," she said.

The train was en route from Los Angeles to Marion, Ark., when it derailed in the Los Angeles suburb of Pico Rivera (search). One resident was treated at the scene for injuries caused by debris, Castro said.

Derailed cars battered two homes and littered several back yards with twisted metal and debris. One boxcar went through the roof of a home, and two others smashed into a wall outside a house next door.

"We want to extend an apology to members of the community for this accident and for the imposition on their lives," Blackwell said. "We are going to do what we can for them."

A Red Cross evacuation center was opened at a nearby high school, and Union Pacific arranged for displaced families to stay at nearby hotels.

Sara Fabela, 33, was home when she heard the train approaching. She thought the ground was shaking more than it usually does when trains pass, then she heard a loud crash and the lights went out.

"I opened the door and there was thick black smoke everywhere. The smoke had a funny smell," she said.

Fabela, who is five months pregnant, said she developed a headache soon after the accident and was concerned about the health of her fetus.

"They say it was small amounts (of hazardous materials), but you never know," she said.

Blackwell said some of the containers carried butane lighters, but no leaks were reported from those. John Mancha, Los Angeles County fire inspector, said there also were small quantities of sulfuric acid and a resin solution on board. The National Transportation Safety Board (news - web sites) was investigating.

The accident was Union Pacific's second in as many years in the Los Angeles area.

In 2003, 13 people were injured and several homes were damaged or destroyed when a Union Pacific train jumped the tracks in Commerce, Calif., about 10 miles from Pico Rivera. Local leaders criticized the railroad's emergency procedures following the incident.