The two siblings were rushed to Northern Hospital of Surry County by their father, Graig Allen Sheff, the Surry County Sheriff's Office said. The boy was treated and released, and the girl was reported in stable condition after she underwent surgery.
Investigators did not elaborate on what may have triggered the shooting beyond "road rage."
Surry County officials identified Byron Donnell Green, 41, as the suspect and found him at his apartment in Mount Airy, Winston-Salem station WXII-TV reported.
Green was charged with assault with a deadly weapon with intent to kill inflicting serious injury, discharging a weapon into an occupied property causing bodily injury and assault by pointing a gun, police said.
Green was being held at the Surry County Detention Center on $600,000 bond.
The Associated Press contributed to this report.