The victim was in the truck, which burst into flames.
About 50 passengers were aboard train No. 210 from the Santa Clarita Valley to Los Angeles when the accident happened at about 9:30 a.m., authorities said.
The truck drove onto the tracks at a crossing where the gates were down and the signal lights were flashing, witness Greg Peale told KABC-TV. Investigators had no immediate comment.
In addition to the one fatality, 20 people were injured, said police Sgt. Craig Ratliff, who described the injured as ``walking wounded.''
Firefighters pulled some passengers from the wreckage and set up a triage area to treat the injured. Some passengers carried the injured from the upended cars before firefighters arrived. Passersby used a metal girder to smash the window of a door on one upended passenger car and helped other people to safety.
The train had four passenger cars and an engine at the rear. In that mode the train is operated by an engineer in a cab of the lead passenger car.
Burbank is about 10 miles northwest of Los Angeles.
It was the worst Metrolink accident since a commuter train was struck by a freight train April 23 in Placentia, killing two people and injuring more than 200.
Investigators believe that crash was caused when the crew of a Burlington Northern-Santa Fe freight train ran two warning signals before plowing into the double-decker Metrolink train. The freight engineer told police he was blinded by the sun and missed a crucial signal light.
Metrolink operates commuter trains over seven routes in six Southern California counties. It carries about 33,500 riders on 138 trains each weekday. The service began in 1992.
