The accident occurred about a half-mile from the /*Metrolink*/ station in Rialto, about 60 miles east of downtown Los Angeles.
"Although this incident occurred at a low speed, any incident on the Metrolink system is unacceptable," Metrolink Board Vice Chairman Keith Millhouse said. "This incident will be fully investigated to determine the cause, and measures will be taken to ensure that incidents like this do not happen again."
The accident came just about 10 weeks after the deadliest crash in Metrolink history. On Sept. 12, a Metrolink train and Union Pacific freight train collided head-on in the Chatsworth area of Los Angeles, killing 25 people and injured 135. Both trains were going about 40 mph.
The deadly crash was blamed on the failure of the Metrolink engineer to stop at a red light so the oncoming Union Pacific train could go by. Investigators have said the engineer, Robert Sanchez, sent a text message seconds before the impact, which killed him.
It's unclear whether the Metrolink engineer in Thursday's crash missed a signal. Metrolink spokeswoman Joanna Capelle said the locomotive was staffed by an engineer and one other person, in accordance with new safety procedures instituted after the Chatsworth crash.
The 102-car freight train had almost made it onto the side track when the Metrolink struck a flatbed car hauling iron, BNSF spokeswoman Lena Kent said.
According to Metrolink, the trains "came into contact at low speed" in a "minor sideswipe, not head-on." The collision did not damage the passenger coaches, freight cars, tracks or signal facilities, the agency said.
Capelle said four people were taken to the hospital with minor injuries.
Salvador Lara, 37, said he was waiting in his truck at a railway crossing shortly before the collision and saw the Metrolink train coming up the tracks.
"I was waiting for (the train) to pass and I heard a boom," Lara said in Spanish, standing on the tracks and watching railroad employees survey the collision site.
Lara said he later saw ambulances arrive and several passengers taken off the train on stretchers.
The freight train's three crew members were not hurt, Kent said, nor were the two people in the Metrolink locomotive.
Officials from the National Transportation Safety Board and the Federal Railroad Administration were investigating.
