(CNN) -- One person was killed and 13 were injured Monday when a church bus returning from a weekend retreat wrecked on a California mountain highway, authorities said.
The bus went over the side of the road near Crestline in the San Bernadino Mountains, and down a grade after colliding with an SUV, according to Officer Mario Lopez of the California Highway Patrol. The location -- in mountains about 75 miles east of Los Angeles -- made it difficult for emergency responders who had to make their way up a mountain road to get to the wreck and for helicopters that flew in to airlift victims.
Describing the rescue, Lopez said, "My understanding listening to the radio traffic was that the road had to be shut down to be able to land the rescue helicopters."
Ten of the injured were taken to Loma Linda Hospital. Among those transported were five minors.
Late Monday night, one of the victims was in critical condition; four in serious; and the rest in fair condition, said hospital spokeswoman Briana Pastorino.
Three others were airlifted to Arrowhead Hospital in Colton. Arrowhead nursing supervisor Pam Shellner told CNN that one patient was in critical condition, one was listed as stable and the third was being assessed.
The bus was carrying teenage students heading home from a weekend church retreat, according to Daniel Lee, head of transportation for Light of Love Mission Church in Pasadena. A church volunteer was driving the bus, Lee said.
The highway patrol said the accident was under investigation.
CNN's Sara Weisfeldt, Carey Bodenheimer and Greg Morrison contributed to this report.