A mudslide happened around 7 p.m. near Las Posas Road, causing vehicles to get stuck in the mud and water. It was unclear how many vehicles were stuck.
Drivers said it happened fast - a pool of rocks, branches and mud gushed over the highway, bringing traffic to a sudden stop.
A California state parks vehicle was heading to reports of another mudslide, when it got stuck in the middle of a road.
Then about half a mile north of Neptune's Net, heavy flooding was reported. Another area that experienced a mudslide was in Encinal Canyon.
One couple ended up with an inoperable vehicle after hitting a rock when they tried to find an alternate route.
Another driver, Camarillo resident Paul Dalton, said he was on his way home when he got stuck in between mudslides.
"I was on my home, got stopped at a mudslide over there, turned back to take maybe Kanan Road or anything, but then I got stopped here and trapped in the middle," he said.
Authorities said PCH was closed from Las Posas Road in Ventura County to Encinal Canyon Road in Malibu.
No injuries were reported.
Residents in the area said the mud seemed to keep coming and they had to wade through several inches of the muck to get to their house.
Caltrans tweeted that the highway would be closed until Sunday while crews worked to clean up the mess.
Flash flood warnings were in effect for all areas affected by the Woolsey Fire in Ventura and Los Angeles counties.
About an inch of rain was expected to fall in many parts of the Southland as a storm system moved through the region Saturday night.