But when the tour bus they were riding in careened out of control and collided with a car and truck as it came down the mountain from the ski resort town of Big Bear, they found themselves in a scene more gruesome than any they had seen back home.
"I saw many people dead. There are very, very horrendous images in my head, things I don't want to think about," Barrientos, who works in a hospital pharmacy, said Monday.
Authorities said seven people died and three dozen others were injured in the wreck Sunday.
"I was overwhelmed," said Ramirez. "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."
A day after the crash, they were waiting outside the Loma Linda University Medical Center emergency room to hear about the condition of their friend, another medical resident whose neck was broken.
Barrientos, who was uninjured, sprang into action following the crash, moving his friends to safety. He 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.
The severity of the injuries made it difficult for authorities to determine how many people had died. They initially said eight, then reduced the number to seven Monday after determining no more bodies were in the wrecked bus.
The dead included San Diego residents 13-year-old Victor Cabrera-Garcia, Elvira Garcia Jimenez, 40, and Guadalupe Olivas, 61; and Tijuana residents Aleida Adriana Arce Hernandez, 38, Rubicelia Escobedo Flores, 34, and Mario Garcia Santoyo 32, said San Bernardino County coroner's supervisor Tony Campisi. One woman remained unidentified.
Just before the crash, the driver had shouted to the passengers that the brakes had failed, and urged them to call 911.
As passengers frantically tried to get a cellphone signal, a group of teenage girls shrieked and prayed aloud. 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.
The crash littered Route 38, a two-lane highway in the San Bernardino National Forest 80 miles east of Los Angeles, 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.
Federal investigators at the scene said they would begin on Tuesday a thorough investigation of the bus and the circumstances that surrounded the crash. They will determine if mechanical failure or driver error was to blame.
Government records showed the bus, operated by Scapadas Magicas LLC of National City, Calif., recorded 22 safety violations in inspections in the year ending 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 driver, Norberto B. Perez, 52, of San Ysidro, suffered major injuries but before going to the hospital told authorities the vehicle had brake problems.
A person involved in the investigation who spoke on condition of anonymity because the probe was ongoing said the bus was moving slowly downhill and was 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.
At least 17 people remained hospitalized Monday, including at least five in critical condition.
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.
Garcia said 38 people were aboard the bus that crashed, including the driver and a tour guide. The bus left Tijuana at 5 a.m. Sunday and planned to 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.
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 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.
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Associated Press reporters contributing to this report included Julie Watson in San Diego, Raquel Maria Dillon in San Bernardino County and Michael R. Blood, Andrew Dalton and Bob Jablon in Los Angeles. Flaccus reported from Loma Linda, Calif.
