The collision was reported shortly before 11 a.m. just east of Pennsylvania Avenue, according to a California Highway Patrol incident log.
One person was transported to a hospital in unknown condition, according to the Los Angeles County Fire Department.
The cause of the crash was under investigation.
There was no estimate of when the westbound side of the freeway would be reopened. Eastbound traffic was unaffected by the crash.
The collision followed an earlier single-vehicle incident on the westbound 210 Freeway in nearby Sunland, where a big rig was engulfed in flames that spread to nearby brush before being extinguished by firefighters.