Updated

A tour bus crossed into oncoming traffic and hit two cars in the Southern California high desert Monday, killing a woman and injuring 26 others.

California Highway Patrol Officer Brian Benson said it was unclear why the bus crossed into the westbound lanes of State Route 58 near Kramer, about 100 miles northeast of Los Angeles.

Benson said a 55-year-old woman in one of the cars was killed. San Bernardino County Fire spokesman Eric Sherwin said nine people suffered life-threatening injuries and 17 others were also taken to hospitals.

Benson said the bus, owned by Arcadia, California-based A&F Tours Inc., seats about 30 passengers. The company had no immediate comment.

The company's vehicles have been inspected 22 times in the last two years, and a vehicle was taken out of service during one of the inspections, according to U.S. Department of Transportation records. The company did not report any crashes in the last two years, the records showed.

Duane DeBruyne, a spokesman for the Federal Motor Carrier Safety Administration, said the agency would assist in a post-crash assessment, including an examination of both the vehicle and the bus company's safety record.

Benson said it was unclear what caused the crash, adding that there was no remarkable weather in the area at the time of the collision.

After hitting the two cars, Benson said the bus turned over on its side and somehow righted itself.

Video footage at the scene posted online shows debris strewn all over the side of the highway as firefighters worked to remove the victims from the cars. The footage also shows firefighters placing a woman in a neck brace and carrying another on a stretcher, a woman comforting a puppy and a man holding a child. The front end of the bus was badly damaged.

The Associated Press contributed to this report.