Deputies say one man went inside wearing a black ski mask Thursday shortly after 5 p.m. and pointed a shotgun at a clerk.
Initially the clerk thought it was a hoax, but then the man fired a shell into the ceiling.
Officials say the gunman ran out with some cash, and then left in a silver, older model Jeep Cherokee, which was driven by a white female.
Authorities described the gunman as a male, possibly Hispanic, 5 foot 9, 180 pounds, wearing a black coat and black mask.
No injuries were reported.
Anyone with information about the robbery is asked to contact the Johnston County Sheriff's Office at (919) 989-5000.
With information from Mickey Lamm/WTSB Radio