York County Coroner Sabrina Gast said in a news release Monday that the victims were 35-year-old Ebony Tamia Roscoe of Charlotte and her 3-year-old son, Malik Josey Easley.
Gast said both of them died at the scene Saturday night near Rock Hill.
She said autopsies are planned.
The South Carolina Highway Patrol says Roscoe was driving south in the northbound lane when her car hit a tractor-trailer rig. Two other people in Roscoe's car were taken to a Charlotte hospital for treatment.
Cpl. Bill Rhyne says the neither the truck driver nor a passenger in the truck were hurt.
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