Photo: The Canadian Press. All rights reserved.

A California Highway Patrol officer stands near the crash scene where at least eight people were killed and nearly two dozen were injured when a bus carrying a group from Tijuana, Mexico crashed with two other vehicles on its way back from Big Bear Lake on Highway 38 north of Yucaipa, Calif., Sunday, Feb. 3, 2013. Both sides of the highway remained closed two and a half hours after the crash and it was unclear when it would reopen. (AP Photo/The Sun, Rick Sforza) 

At least eight and as many as 10 people were killed and more than three dozen injured when a bus careened out of control while travelling down a Southern California mountain road, struck a car, flipped and plowed into a pickup, authorities said.

California Highway Patrol spokesman Mario Lopez said the number of eight confirmed deaths was expected to rise because the coroner was just starting to remove bodies from the mangled vehicle and also remove the bodies of those who were ejected, which were covered by yellow blankets.

"It appears speed was a factor in this collision," Lopez said. Investigators will determine if mechanical failure or driver error was to blame, he said. The driver survived.

Authorities had not yet obtained the passenger list from inside the bus, Lopez said.

The accident occurred around 6:30 p.m. about 80 miles (130 kilometres) east of Los Angeles and left the highway littered with debris, the bus sideways across the two lanes and its front end crushed.

The bus was returning to Tijuana, Mexico, Lopez said. It rear-ended a Saturn sedan and hit a Ford pickup, he said. One person in the pickup was injured. The fate of the passengers in the car was not clear, but at least two people were in it, Lopez said.

California Department of Transportation spokeswoman Michelle Profant said the scene was shocking.

"It's really a mess up there," she said.

The bus driver told investigators the bus suffered brake problems as it headed down the mountain, Lopez said.

Lettering on the bus indicated that it was operated by Scapadas Magicas LLC, a company based in National City, California. Federal transportation records show that the company is licensed to carry passengers for interstate travel and that it had no crashes in the past two years.

A call to the company was not immediately returned.