Workers Saturday began removing the wreckage of a runaway freight train that derailed, demolishing homes and killing four people. One survivor was found after 14 hours buried in the train's sandy cargo.

A precautionary search for more victims was conducted after the fourth body was found early in the day, even though there were no reports of anyone missing. The search ended in the afternoon, and heavy equipment began removing train cars that flew off curving tracks on Friday, said police officer John Montecino.Federal investigators began to try to determine how the wreck happened Friday morning when a freight train went out of control and left the tracks, demolishing six houses and damaging five others.

James Kolstad, acting director of the National Transportation Safety Board, told reporters at the crash site that the cause was unknown.

Twenty-nine families were ordered to stay out of their homes as a precaution because rail cars lay atop an underground pipeline that might be affected when the cars are moved, said Red Cross chapter manager Robert Wussler. The Red Cross had already put up 200 residents in hotels Friday night.

The 69-car Southern Pacific freight hauling a sandy mineral raced down 4,109-foot Cajon Pass between the San Bernardino and San Gabriel Mountains, derailed on a curve and hit 11 homes about 7:40 a.m. Friday.

The crew radioed to a dispatcher that it was out of control at 90 mph.

"The train was all over the place," said a witness, Al Dorame. "It looked like a toy in a sandbox. Some of the people thought it was an earthquake."

The dead were identified as stepbrothers Jason Thompson, 9, and Tyson White, 7; conductor Everett S. Crown, 36, a 17-year Southern Pacific employee; and brakeman Allan R. Reiss, 44, an 18-year employee, whose body was not found until Saturday morning.

Three trainmen and six other people were injured.

One of the injured, Christopher Shaw, 24, survived for hours under the wreckage. He was found Friday evening in a pocket of air under rail cars and the sandy cargo that crushed his home. He had surgery to have a pin put in a broken leg and was in serious condition at San Bernardino County Medical Center, said nursing supervisor Helen Ramirez.

Shaw was half-asleep when his home was flattened. He lay there all day and into the night before he was found, still conscious beneath the rubble.

Rescuers extended an oxygen tube and encouraged him during the 11/2 hours it took to free him. Debris had apparently formed a cave with enough oxygen to sustain him, said Gene Brooks, a rescue supervisor.

The train was going from Mojave in the high desert to Long Beach with a load of sodium carbonate and sodium bicarbonate, components of potash, a mineral used to make fertilizer and soap, railroad spokesmen said.

The tracks were expected to remain closed, forcing the detour of 15 freights and two passenger trains.