Marion County Coroner Jerry Richardson says Kelsey Mitchell Day, 19, of Columbia and Ronald Frenchshaw Davis Jr. of Johnsonville died after their vehicles collided on Highway 378 in Marion County.
The crash happened around 3:50 a.m. Sunday near the Horry County line, said Richardson.
Davis died at the scene, and Day was taken to Grand Strand Regional Medical Center where she later died from her injuries, Richardson added.
According to Lance Cpl. Sonny Collins, Davis' 1995 Crown Victoria was traveling east on Hwy. 378 and Day's Suzuki SUV was traveling west on Hwy. 378.
Davis was not wearing a seat belt and Day was, said Collins.
Highway Patrol is investigating the crash to see which vehicle crossed the center line to cause the collision.
