Ten people were killed when a FedEx truck struck a charter bus carrying high schoolers head-on in Northern California yesterday evening, authorities say.

According to the Los Angeles Times, the truck crossed over a median on Interstate 5, colliding with a Silverado Stages bus carrying a group of students from the Los Angeles-area around 5:30 p.m. Witnesses told the Times that the crash sounded like "a series of explosions," and caused both vehicles to erupt in flames. 

A California Highway Patrol Patrol dispatcher told the Times that five victims were students, three were adult chaperons, and that the drivers of both vehicles were killed. The Times adds that the bus was traveling to Humboldt State University in Arcadia, Calif. for a college tour. 

Officials say several students were transported to various area hospitals, some in critical condition. The identities of the deceased have not been released, and Los Angeles Unified School District officials are still working to determine which students were involved in the tragic accident because there were three buses carrying students from various districts on the trip.

FedEx released a statement saying the company is "cooperating fully" with the investigation.

[via Los Angeles Times]