An 18-year-old from New Underwood died Friday afternoon after her car hit the rear of a semi that was parked on the shoulder of westbound Interstate 90 about 12 miles east of Rapid City.

The South Dakota Highway Patrol identified the victim as Jennifer Lynn Vance.

The patrol said the truck driver, Alexei V. Markov, 34, of Westmont, Ill., had pulled over and parked the rig because of mechanical problems. Warning devices had been placed behind the truck.

Troopers say Vance's car, a 1996 Chevrolet Cavalier, had drifted onto the shoulder of the road just before the crash at 12:45 p.m.

Alcohol was not involved. Vance was wearing a seat belt and died at the scene, the patrol said.