At about 12:20 a.m. Saturday, three males went into Kit Kat Pizza on Gottingen Street wearing ski masks.
All three were armed with hand guns and demanded cash from the elderly owner, said Staff Sgt. Reid McCoombs said in a news release.
When the owner didn't comply, one of the suspects struck him with the butt of his gun.
The suspects then grabbed numerous cartons of cigarettes and took off on foot.
The store owner received a cut to his head and was taken to hospital.
Police are looking for three suspects, one as young as 14 years old.
Police are asking anyone with information to get into contact with them.