OXNARD, Calif. (AP) — A Southern California commuter train slammed into a truck abandoned on the tracks early Tuesday, sending three rail cars tumbling onto their sides and injuring 28 people in the fiery crash.

The accident occurred around 5:45 a.m. in Oxnard, about 65 miles northwest of Los Angeles. Four people, including the train engineer, had critical injuries.

The truck driver was found several miles away, and authorities are questioning him about why the vehicle was left on the tracks.

Little was left of the truck except scorched and mangled wreckage, with some debris found in a nearby intersection and some close to the tracks.

The Metrolink train carrying 48 passengers and three crew members was heading from Ventura County to Los Angeles. The injured people were taken to several hospitals.