The crash was reported at 3:20 a.m. on the eastbound Glenn Anderson Freeway east of Garfield Avenue, according to the California Highway Patrol.
Witnesses reported a Toyota Prius in the HOV lane was fully engulfed in flames and that the driver was still inside.
One person was confirmed dead at the scene at 3:35 a.m., said CHP Officer Patrick Kimball.
The incident was first reported as a three-vehicle collision but more vehicles were reported on the right shoulder
A SigAlert was issued at 3:50 a.m. shutting down all eastbound lanes of the Glenn Anderson Freeway west of the Long Beach (710) Freeway and diverting traffic off at Garfield Avenue. Lanes 4 and 5 were reopened about 5 a.m.