SAN PABLO (CBS SF) — A westbound Amtrak passenger train slammed into a semi-trailer truck carrying a load of vehicles Monday night at a crossing near San Pablo, jolting passengers, derailing the engine and leaving a massive pile of debris scattered across the tracks.

Authorities said the collision took place at the crossing on Soto and Market streets about 8 p.m. The truck had somehow stalled on the tracks.

READ MORE: KPIX Reporters Remember Slain Security Guard Kevin Nishita; 'Just the Kindest Man'

“A tracker trailer carrying vehicles got high centered on the railroad tracks and got struck,” said Rodeo/Hercules Fire Battalion Chief Darren Johnson. “They couldn’t get the tracker off the tracks prior to the train coming through. The train hit the tracker, all the cars came off the vehicle.”

The train was carrying 30 passengers who who were shaken, but otherwise uninjured. They were boarded onto buses and taken to a nearby Amtrak station where they continued on to their holiday destinations.

READ MORE: UPDATE: News Crew Security Guard Shot in Oakland Dies From Injuries; Photo of Suspect Vehicle Released

The force of the impact derailed the engine, separating it from the passenger cars and left piles of wreckage around the tracks.

“The engine is off the tracks,” Johnson said. “There was one injury to the engineer.”

MORE NEWS: Burlingame Shoppers Show Up for Small Business Saturday

The collision remains under investigation. Union Pacific work crews worked over night to get the engine back on the tracks and clear debris.