The California Highway Patrol issued a Sigalert for southbound lanes near Santa Monica Boulevard at about 9:20 p.m. after receiving a call regarding a pedestrian on the freeway.
Los Angeles police said they received reports of a person running in and out of traffic. As officers attempted to stop the man and remove him away from traffic, he jumped over a railing of the overpass and fell onto the freeway, according to police.
Police said the man, who appears to be a transient, was believed to be under the influence of alcohol.
CHP said lanes would be blocked for at least an hour and later reopened two lanes at about 10:33 p.m. Closures for all lanes were lifted at 3:32 a.m. Wednesday.
Police and CHP were at the scene investigating.