The crash occurred shortly after 4 a.m. near Baldwin Park Boulevard, blocking four lanes on the westbound side, the California Highway Patrol said.
At least one person was killed in the crash that involved three vehicles. The identity of the victim was not known.
AIR7 HD showed only one lane open.
It was not immediately known what led to the crash.
CHP said the four lanes would be shut down for an unknown duration. All lanes were reopened shortly before 7:30 a.m.