The California Highway Patrol's Southern Division, which covers the greater Los Angeles area, responded to 388 accidents between 4 a.m. and 8 a.m.
A jackknifed big rig blocked multiple lanes on the westbound 118 Freeway just past the 405 Freeway in the Mission Hills area shortly before 4 a.m.
Fortunately, the big rig did not strike any other vehicles, and no one was injured.
There were several other accidents involving jackknifed big rigs - including on the westbound 210 Freeway near the 134 Freeway in Pasadena. The crash had multiple lanes shut down for hours.
Another jackknifed big rig shut down multiple lanes on the northbound 710 Freeway at the 105 interchange in the Lynwood area, causing heavy backups.
A wreck involving four to six vehicles created parking-lot conditions on the westbound 10 Freeway near Soto Street in the Lincoln Heights area around 5:30 a.m.
The heavy rain caused serious flooding on the northbound 5 Freeway at Lankershim Boulevard in Sun Valley. Caltrans crews busy for three hours pumping out the water before they could reopen the lanes.
There were also multiple incidents of flooding, including on the southbound 110 Freeway at Adam Street in Los Angeles. Newport Beach police warned commuters to avoid northbound Newport Boulevard between Coast Highway and Hospital Road due to flooding.