A Southern California commuter train collided with a box truck Tuesday, sending 21 passengers to the hospital with minor injuries. 

The crash occurred at approximately 10:40 a.m. local time near the Sun Valley Metrolink station, north of downtown Los Angeles. The Los Angeles-bound train was carrying 190 passengers, according to the Los Angeles Fire Department. 

Witnesses told KTLA the truck was in the middle of the tracks when the railroad crossing arms went down, the red lights started flashing and the bells began ringing. The truck's driver was not injured, officials said.

“I just heard like a big boom when the trailer was trying to pass by quick,” witness Jose Zamaniego told the station. “I thought it was a big crash but I didn’t see anything bad."

The train continued toward Los Angeles after injured passengers were removed for treatment. Officials warned passengers to expect delays of nearly two hours after the crash. 

The Los Angeles Times reported that the railroad crossing where Tuesday's accident occurred had seen at least 15 collisions between trains and vehicles since 1993.