All northbound lanes were closed at about 2:30 p.m. PDT, and only one southbound lane was open -- resulting in major backups in both directions on the heavily traveled freeway.
The California Highway Patrol imposed detours through residential and commercial areas, and ordered heavy equipment into the area to clear the obstructed lanes, the Los Angeles Times reported.
The first major Southern California storm of the season caused flooding, which in turn sent rocks, mud and debris down hillsides onto the freeway.
Water in some places was deep enough to cause several vehicles to stall, CHP said.
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