YUCAIPA, Calif. – The bus full of tired tourists returning to Tijuana, Mexico, was slowly winding down a mountain road from the ski resort town of Big Bear when it suddenly picked up speed. The driver shouted to call 911 – the brakes had failed.

As passengers frantically tried to get a cellphone signal, a group of teenage girls shrieked and prayed aloud as others cried and shielded their heads as they careened downhill.

The bus rear-ended a Saturn sedan, swerved, flipped and slid on its side. A Ford pickup in the oncoming lane plowed into it, righting the bus and tossing passengers out shattered windows before it came to a halt.