Authorities say as many as 90 vehicles were stranded after mud and debris flowed down the hillside along a 12-mile stretch of Angeles Crest Highway in Southern California.
Los Angeles County Fire Capt. Frank Reynoso says about half of the vehicles had been freed Saturday afternoon but at least 40 cars remain stuck.
Rescue workers are walking some of the occupants to safety. Reynoso says some vehicles will have to be abandoned and retrieved at a later date. No injuries have been reported.
Multiple landslides have been reported on a state route between La Canada Flintridge and Mount Wilson.
The California Highway Patrol says the road will be closed indefinitely.
A flood watch for Los Angeles County lasts through Sunday morning.