A collision involving two vehicles was reported at about 2:25 a.m. just south of Pacifica near Devil's Slide, CHP Officer Aaron Quistad said.
One victim sustained major injuries and three or four more received minor injuries in the accident, which reportedly forced one vehicle off the narrow Pacific Coast Highway, falling more than 150 feet down a sea cliff, Quistad said.
Officers and emergency crews transported the accident victims to San Francisco General Hospital, Quistad said, where an evaluation will be made to determine whether alcohol played a part in the crash. CHP has advised motorists in the area to use alternate routes.
A Sig-alert was issued at about 3:45 a.m.