LEGGETT (CBS SF) — A massive landslide has shut down Highway 101 in northern Mendicino County and will likely not be cleared until sometime Friday, officials said.

The California Highway Patrol said the slide occurred about 6 miles north of Leggett late Sunday night.

The highway had been reduced to one lane since a another landslide triggered by months of rain had sent tons of debris down onto the roadway on March 10th. Since that time, Caltrans crews have been trying to remove the debris and also strengthen the hillside.

However, the weakened hillside gave way again.

Caltrans was advising travelers heading north to Humboldt County and beyond to use Highway 5.

The CHP also warned motorists not to trust GPS in their efforts to find a way around the slide. Travelers were being routed by their GPS to take Usal Rd. around the closure. But the road is really a 4×4 trail and numerous motorists have become struck.