ORLAND, Calif. — Investigators do not yet know what caused a FedEx tractor-trailer to veer across a grassy highway median and slam into a bus, killing 10 people, but they are looking into various factors, the California Highway Patrol said Friday.
Those factors include whether the FedEx driver fell asleep, experienced mechanical failure or lost control because of a separate collision on the southbound side of the freeway.
Authorities also will probe roadway and weather conditions, Lt. Scott Fredrick said at a news conference.
The bus was carrying more than 40 high school students on their way to visit Humboldt State University when the FedEx tractor-trailer swerved across a grassy highway median and slammed into their bus in a fiery wreck Thursday.
The crash occurred Thursday near Orland, a city about 150 miles (250 kilometres) northeast of San Francisco.
“Since these are such in-depth, detailed investigations, we don’t expect to have a final report for a minimum of three months, 90 days,” Fredrick said. “It could take as long as six months depending on what the investigation entails.”
Someone kicked out a window on the bus, and many of those aboard squeezed through and ran for their lives before the vehicle exploded in flames.
The 44 teenagers aboard, nearly half from the Los Angeles school district, were participating in a program that invites prospective low-income or first-generation college students to visit Humboldt State University in far Northern California.
Both drivers were killed, along with three adult chaperones and five teenage students, according to the California Highway Patrol.
Towering flames devoured both vehicles just after the crash, and clouds of smoke billowed into the sky until firefighters doused the fire, leaving behind scorched black hulks of metal. Bodies were draped in blankets inside the burned-out bus.
The National Transportation Safety Board sent a team to investigate.
“Every piece of paper associated with this will be looked at,” said Eric M. Weiss, an NTSB spokesman.