The collision happened just before 2:30 a.m. at Norwalk Boulevard, according to the California Highway Patrol. Officials say multiple vehicles were involved, but it's unknown exactly how many.
Three people were found dead at the scene and two others were taken to the hospital in unknown condition.
Multiple freeway lanes were shut down as a result of the deadly crash, the cause of which remains under investigation.
DEVELOPING: We will add more details to this report as they become available.