YUCAIPA, Calif. (AP) -- Federal and state investigators hunted Tuesday in the mangled wreckage of a California tour bus for the cause of a weekend crash that left seven people dead and injured dozens of others.
Authorities targeted the brakes and other equipment for clues to why the driver lost control on a two-lane mountain highway in the San Bernardino Mountains on the way back to Tijuana, Mexico, after a trip to the snow.
The roadworthiness of the 1996 bus loomed as a key issue after the driver told investigators the brakes failed as he descended from the popular ski area of Big Bear. Federal records pointed to a history of brake-maintenance problems with the European-made bus.
"We are going to look very closely at the brakes as we will every other mechanical system on the bus," National Transportation Safety Board spokesman Eric Weiss said.
Launching a review that could take months, investigators for the California Highway Patrol and NTSB began collecting evidence on the bus, road conditions and possible driver error or fatigue that could have played a role in the crash.
A team of NTSB officials was dispatched to the offices of bus operator Scapadas Magicas LLC, in National City, Calif., where they interviewed owners and employees, and gathered documents on the maintenance history of the bus, Weiss said.
The bus, its front roof collapsed and windows shattered, was towed to an auto yard in Ontario that the CHP uses to store evidence, Officer Mario Lopez said.
"They're going to comb through and determine whether there are any safety issues," Lopez said. "It's a very intricate process."
The bus was carrying 38 people, including the driver and a tour guide, when it left Tijuana at 5 a.m. Sunday for a daylong trip. It was returning on State Route 38, which meanders through San Bernardino National Forest, when the accident occurred around 6:30 p.m.
The dead included San Diego residents Victor Cabrera-Garcia, 13, Elvira Garcia Jimenez, 40, and Guadalupe Olivas, 61; and Tijuana residents Liliana Camerina Sanchez Sauceda, 24, Aleida Adriana Arce Hernandez, 38, Rubicelia Escobedo Flores, 34, and Mario Garcia Santoyo 32, authorities said.
Just before the crash, the driver had shouted to the passengers that the brakes had failed and urged them to call emergency services.