The accident happened shortly before 2 a.m. on the southbound lanes at Del Amo Boulevard.
The driver of the tractor-trailer said he was cut off by another vehicle. He swerved and lost control of the big rig.
The crash spilled debris onto the northbound lanes, causing two other cars to collide. No injuries were reported.
Southbound lanes of the freeway were closed until after 6 a.m. as crews cleared the scene.