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.

“Everything happened so fast. When the bus spun everything flew, even the people,” said Gerardo Barrientos, who was next to his girlfriend one minute and then scrambling out of the wreckage the next trying to find her and a friend in the highway. Both were injured but alive.

Seven people were killed and about three dozen injured Sunday night in the accident 80 miles east of Los Angeles. The dead included 13-year-old Victor Cabrera-Garcia; Elvira Garcia Jimenez, 40; and Guadalupe Olivas, 61, all of San Diego; along with Aleida Adriana Arce Hernandez, 38, and Rubicelia Escobedo Flores, 34, and Mario Garcia Santoyo 32, all of Tijuana, said San Bernardino County coroner’s supervisor Tony Campisi.

One woman remained unidentified.

On Monday, while families of the tourists descended on area hospitals looking for loved ones, investigators searched for evidence and scrutinized the bus company’s safety history.

Government records showed the bus, operated by Scapadas Magicas LLC of National City, Calif., recorded 22 safety violations in inspections in the year ending last October — including brake, windshield and tire problems. Though the company retained an overall “satisfactory” rating from the Federal Motor Carrier Safety Administration it had been targeted for a higher rate of inspections linked to bus maintenance, the agency said.

The National Transportation Safety Board sent a team to the scene to help in the investigation, which will determine if mechanical failure or driver error was to blame. The driver, Norberto B. Perez, approximately 52, of San Ysidro, was injured but before going to the hospital told authorities the vehicle had brake problems.

The bus was returning to Tijuana on State Route 38, a two-lane highway that meanders through San Bernardino National Forest, when the accident occurred around 6:30 p.m.

A person involved in the investigation who spoke on condition of anonymity because the probe was ongoing said the bus was going slowly down the hill and was being passed by other vehicles, including the Saturn, when it suddenly sped up.

The bus traveled about a mile from the point it struck the Saturn until it came to a stop, California Highway Patrol Officer Leon Lopez said.

Maria Salazar’s daughter, 28-year-old Diana Maldonado of San Diego, was among those injured. Salazar said her daughter described the terror of the bus flipping and her head smashing through a window as she was propelled out of the vehicle. She lost consciousness and awoke as paramedics tended to her.

Maldonado hurt her back and shoulder but remarkably did not break any bones, according to her mother, who said her two other daughters had planned to make the trip but did not.

“I just thank God they did not go,” Salazar said in Spanish as she choked back tears.  

The crash littered Route 38 with body parts, winter clothing and debris. The bus stood across both lanes with its windows blown out, front end crushed and part of the roof peeled back like a tin can.

“I saw many people dead. There are very, very horrendous images in my head, things I don’t want to think about,” Barrientos said as he and girlfriend Lluvia Ramirez, who both work at a government hospital in Tijuana, waited outside the Loma Linda University Medical Center emergency room for word on a friend who broke her neck.

Barrientos, who was uninjured, quickly sprang into action following the crash, moving his friends to safety and then tried to help the bus driver, whose hand was pinned between rocks. Ramirez, who had a bloody ear, dark bruises and a scratch on her neck, suffered a hairline vertebra fracture.

“I was overwhelmed,” she said. “I’m a surgical resident and I usually know how to react, but I was so in shock I didn’t know what to do. I just stayed with my friend.”

The gruesomeness of the injuries made it difficult for authorities to determine just how many had died. They initially said eight but then reduced the number to seven after determining no additional bodies were in the wrecked bus.

At least 17 people were still hospitalized Monday, including at least five in critical condition.

The bus driver had major injuries, Lopez said, and the pickup driver was in extremely serious condition, said Peter Brierty, assistant county fire chief.

No one answered the door at the Scapadas Magicas office in a sprawling complex that houses more than 1,300 storage lockers and about 30 small offices.

Jordi Garcia, marketing director of Interbus Tours, said his company rented the bus from Scapadas Magicas, which supplied the driver.

Interbus offers near-daily bus tours to the western U.S. from Tijuana. Its office in a Tijuana strip mall displays photographs of some of its destinations, including Hollywood, the Las Vegas Strip and the San Diego Zoo.

There were 38 people aboard the bus that crashed, including the driver and a tour guide, Garcia said. The bus left Tijuana at 5 a.m. Sunday, with the itinerary calling for a return late that night.

He said he spoke briefly with his tour guide, who suffered bruises. She told him she heard a loud pop before the crash.