ELK GROVE (CBS13) – Two people were killed in a crash on Interstate 5 just south of Elk Grove Sunday night, authorities say.

California Highway Patrol says, around 9 p.m., traffic was stopped in the southbound lanes for another crash near Hood-Franklin Road. For an unknown reason, a Nissan sedan slammed into the back of the big rig at 70 miles per hour without hitting the brakes.

The driver and passenger of the sedan died at the scene, officers say. The big rig driver was not hurt.

Authorities have not released the names of the two people killed.

Southbound I-5 was closed for a time but was back open by 11 p.m.

Drugs or alcohol were not factors in the crash, CHP says.