UPDATE (8:29 a.m.) - The SIG Alert at Niblick Rd. has been lifted.
(6:47 a.m.) Southbound Hwy 101 has partially reopened after a full closure at Niblick Rd., CHP says.
The agency issued a SIG Alert at about 6:30 a.m. after the trailer of a semi truck reportedly blocked both lanes of traffic in the area. At about 6:43 a.m., the right-hand lane of traffic reopened.
To avoid the closure, vehicles can exit the freeway at 17th St. or Pine St., officials say, and take the on-ramp at S. Spring St. to return to the freeway.
The initial trailer hazard was reported at about 6:06 a.m. Crews are working to fully clear the area.
This is a developing story. Check back here for updates.