ELK GROVE (CBS13) — The Sacramento County Coroner has identified two 19-year-olds who died in a crash in Elk Grove on Sunday night.

Mariah Alvarado and Cierra Wallace, both of Stockton, died after crashing into the back of a big rig at 70 miles per hour without hitting the brakes, California Highway Patrol investigators said.

MORE: 2 Killed In Crash On I-5 Near Elk Grove

The deadly collision happened on Interstate 5 just south of Elk Grove Boulevard.

The cause of the crash remains under investigation. Drugs or alcohol did not appear to be factors, CHP said.