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.

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

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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.

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