Two people were killed and two others injured in a multivehicle crash on the northbound 405 Freeway in Costa Mesa on Friday night, authorities said.
Few details were immediately provided about the fatal collision, which occurred shortly after 8:30 p.m. near the Harbor Boulevard on-ramp, according to the California Highway Patrol's incident log. About four cars were involved.
The two people who died -- identified only as man and a woman in their late 20s to early 30s -- were in the same vehicle, Costa Mesa Fire Department Capt. Chris Coates said.
A man and a woman in a different car sustained minor to moderate injuries and were transported to a local hospital, according to Coates. Their injuries were not life-threatening.
It was not yet known what caused the crash.
A SigAlert was issued by CHP, and all northbound lanes except for one were shut down for an indefinite amount of time following the collision.
Traffic was backed up on the north side of the road for miles as vehicles slowly made their way past the crash site shortly after 10 p.m., Sky5 aerial video over the scene showed.
The freeway appeared to have been cleared around 11:30 p.m., and all lanes were reopened, according to the incident log.
No additional information was immediately released.
KTLA's Matt Phillips contributed to this story.