One person was killed in a crash on the 405 Freeway in Los Angeles early Thursday morning, forcing a closure of southbound lanes that impacted traffic across a wide area.

The crash was reported around 4:45 a.m. on the freeway near Skirball Center Drive in Brentwood, according to the Los Angeles Fire Department.

First responders found a vehicle had collided with the back of a trailer being pulled by a big rig.

The driver of the vehicle was pronounced dead at the scene, a Fire Department spokesperson confirmed.

Fatal crash on 405 Freeway
Two lanes are closed after a fatal crash on the 405 Freeway on Sept. 21, 2023. (KTLA)

All lanes on the southbound side were closed immediately following the crash. Lanes began to reopen around 6:15 a.m.

Southbound 405 traffic was backed up to the 118 Freeway with some drivers exiting on Sepulveda Boulevard as an alternate.

All southbound canyon routes out of the San Fernando Valley quickly became jammed including Laurel Canyon, Coldwater Canyon, Topanga Canyon and the Cahuenga Pass. Backups also extended in both directions on the 101 Freeway.

The cause of the crash was under investigation.