The crash occurred shortly after 2:30 a.m. on the eastbound side of the freeway near Vernon Avenue.
Multiple vehicles struck the jackknifed big rig, a spokesperson for the California Highway Patrol said. No injuries were reported.
The impact of the crash left the semitruck's trailer straddling the interstate's center median.
Traffic slowed to a crawl on both sides of the freeway as the morning commute got underway.
The cause of the crash is under investigation.