Highway 3 is closed 10 miles north of Weaverville in Trinity County due to a rock slide, the state Department of Transportation reports.
Motorists are advised to use an alternative route. The California Highway Patrol reported the closure at 11:30 p.m. Monday, according to the Redding Record-Searchlight.
There is no estimated time of reopening, Caltrans reports.
Heavy rain saturated soil supporting the highway, leading to the failure, according to Caltrans.