UPDATE (6 p.m.) - Caltrans reports that all southbound lanes of Highway 101 are now open.
(4:35 p.m.) - A SIG Alert was issued for the southbound lanes of Highway 101 in San Luis Obispo Friday afternoon due to a multi-vehicle crash.
It happened shortly before 4:14 p.m. near the Los Osos Valley Road offramp.
CHP was reporting up to five vehicles involved and at least one person suffered minor injuries.
As of 4:22 p.m., southbound traffic was stopped just north of Madonna and both lanes were blocked.
This is a developing story and will be updated as information becomes available.