A bus carrying teenagers and their chaperones home from a weekend religious retreat collided with another vehicle on a treacherous mountain road east of Los Angeles and careened down a steep, snow-covered embankment Monday in an accident that killed one and left at least 10 others seriously injured.

The bus, belonging to a Korean church in Pasadena, was winding its way down the sharp curves of the two-lane California 189 in the Lake Arrowhead region shortly before noon PST, fire and police officials said.

As it rounded a nearly hairpin turn, the bus struck an SUV traveling in the other direction, according to California Highway Patrol Officer Mario Lopez. The bus sheared through a utility pole but remained upright as it plunged about 25 feet into a small grove of cedars and white firs. It slammed into a large tree, Lopez and others said, coming to rest a few feet from a snow-fed stream. The impact crumpled much of the cab.

The driver of the bus, identified by church officials as 61-year-old Won Chae, was killed in the crash, said John Cho, a deacon at the Light of Love Mission Church. Cho described Chae as a former professional tour bus driver who volunteered to drive the church’s bus on weekend excursions. It was not known how long it had been since Chae had driven professionally or if he had the required license.

The cause of the collision remained under investigation Monday evening as authorities tried to sort out whether one of the drivers, road conditions or other factors played a role. At the time of the accident the road was wet from melting snow, but was not icy, authorities said. The skies were clear and the sun bright.

Twenty-two people — most of them teenagers — were aboard the bus, which was not equipped with seat belts. Dozens of firefighters, police and paramedics quickly swarmed the scene. Rescuers had to use special metal-cutting tools to remove seats from the bus in order to extract some of the passengers.

A man who said he was driving past the crash told KNX-AM, “”I hear kids screaming, there’s this bus down. Oh, God, it was terrible.”” The man said he helped rescue two girls, one with a broken leg. He described the other girl as “”dazed and confused.””

“”A lot of them were crying, but this little girl, she’s saying, ‘I’m sorry. I’m so sorry.’ She’s trying to apologize,”” he told the radio station.

A triage area was set up on the road where medical personnel assessed injuries and dispatched the injured to a fleet of waiting ambulances. Within about 90 minutes all 23 of the survivors had been taken to hospitals, with two of the most seriously injured flown by helicopter. The ages of the injured were not known.

The accident snarled traffic in the region as authorities closed a section of California 189 for a few hours.

At Arrowhead Regional Medical Center, where eight of the passengers were admitted, two people had been rushed into surgery, said nursing supervisor Joy Flint. In all, 10 people were listed in critical condition, according to Lopez.

News of the crash sent panicked parents rushing to the small, maroon-shingled church in search of information about their children. Members of one family arrived and then quickly departed for Loma Linda University Medical Center, where their son was being treated for minor injuries.

“”My child was hurt,”” said the mother of another teen as she got into an SUV with her husband, daughter and a church official.

The church has about 1,000 Korean American and Korean immigrant congregants and has been operating for about 18 years, Cho said. Parents of the teens going on the weekend retreat had to sign a release before the trip, officials said.

“”We’re hoping none (of the injuries) are life-threatening. We’re hoping they all pull through,”” Cho said. “”The church is in shock. Faith is what’s keeping us together.”” A prayer service was planned for Monday night.

By Monday evening, some of the victims had been released from Arrowhead hospital. One 18-year-old left the medical center with bad bruises and cuts on his face.