ORLAND (CBS SF) — The California Highway Patrol says the driver of a FedEx delivery truck and a charter bus driver carrying high school students on a college visit are among the 10 people killed in a fiery crash on Interstate 5 Thursday evening.

Three adult chaperons and five teenage students also died in the crash near Orland, about 100 miles north of Sacramento. Their identities haven’t been released.

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National Transportation Safety Board investigators were heading to the scene Friday.

“There will be a number of people representing survival factors, operations, fire safety in this particular case. We also have an investigator from Southern California who’s on his way,” said NTSB board member Mark Rosekind, part of the investigating team from Washington D.C.

“Determining the why, not just the what,” is how Rosekind described the NTSB’s goal.

The CHP reports the bus and truck were on opposite sides of the freeway when the truck crossed a grass median and slammed into the bus, causing an explosion and fire.

Investigators said the truck driver may have been trying to avoid a vehicle on its side of the freeway when he swerved.

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CHP spokesperson Tracy Hoover said the truck then sideswiped a sedan in front of the bus, before striking the bus head on. Both the truck and the bus went up in flames moments after the collision.

The CHP told KHSL-TV that the bus was carrying a group of high school seniors from the Los Angeles area who were planning to tour Humboldt State University in Arcata.

In a written statement, Humboldt State University said the bus was transporting prospective students to the school’s Spring Preview Day.

“Humboldt State University is deeply saddened,” school president Rollin Richmond said in the statement. “Our hearts go out to those who have been affected, and we are here to support them, and their families, in any way possible.”

Governor Jerry Brown issued a statement expressing his sympathies to those who died as well as his gratitude for the Red Cross and emergency personnel who responded.

The school said parents and family members of students on the bus can contact their information line at (707) 826-6327.

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