At least one person was killed in a multivehicle accident that closed northbound Highway 101 at Las Positas Road late Saturday.
Authorities said at least four cars were involved in the crash, which occurred about 10:15 p.m. Saturday on the freeway near Earl Warren Showgrounds. Additional details were not immediately available.
The California Highway Patrol closed the freeway at Las Positas and traffic was backed up for several miles.
Emergency crews are on the scene and the wreckage was still being cleared an hour after the collision. The cause of the crash is under investigation, authorities said.