UPDATE (1:07 p.m.) - All lanes of traffic have been cleared and reopened.
(11:55 a.m.) - Southbound Highway 41 at Cerro Alto Rd. near Atascadero was blocked Monday morning by a four-vehicle crash.
It happened at about 11:40 a.m.
It's unknown when the lanes will be cleared.
This is a developing story and will be updated with new information as it becomes available.