Five high school seniors are among the ten people dead in a fiery crash after a tractor-trailer slammed into their bus on a California highway.

Investigators say the crash happened around 5:30 p.m. on Interstate 5 near Orland, California.  The bus was filled with seniors who were planning a visit to Humboldt State University to see if they wanted to attend in the fall.

The working theory in the investigation is that the FedEx driver was swerving to avoid a passenger car but was unable to avoid them.  The passenger vehicle was involved in the accident with the truck and bus.

In addition to the students, the truck drivers and three adult chaperones were killed in the crash.  At least 37 others sustained injuries, some critically, and about half remained hospitalized.

“As we mourn the loss of those who died, we join all Californians in expressing our gratitude for the tireless work of the Red Cross and emergency personnel who responded bravely to this terrible tragedy,” California governor Jerry Brown said in a statement.