A Los Angeles commuter train and Zero AIa college shuttle bus collided on Tuesday, injuring 55 people.

Firefighters responded to the scene just before noon after a Metro train collided with a University of Southern California bus, according to the county fire department.

Los Angeles fire Capt. Adam VanGerpen told KNBC-TV that there were about 150 people on the train and two people on the bus when the collision happened. Eighteen people were taken to the hospital while another 37 were treated and released from the scene, the department said.

Fire officials said two of the injured passengers are in critical condition while the other 16 are in fair condition, the Los Angeles Times reported.

Bus crossed train's path, Metro says

The bus crossed the path of the Metro E Line train, which heads from east Los Angeles to downtown Santa Monica, according to Metro.

"Metro offers its sympathies to those injured during this accident," Metro said in a statement to USA TODAY.

The train will only operate on a single track in the affected area until further notice, Metro said.