It happened around 1:00 a.m. Friday at 2010 S. Maryland Avenue.
Police say the suspect displayed a silver handgun and demanded money from the cash register.
The clerk fled from the counter area and the robber fired a single shot, but missed.
The clerk then fled the store.
The suspect remained in the store, police said, trying to break open the cash register with no success.
He then stole several packs of cigarettes and fled.
The suspect is described as a black male, 20-29 years of age, 5'6" - 6'0" tall with dark brown complexion. He was last seen wearing a white tank top, dark shirt which was tied around his head and face, dark jeans, and dark shoes.
Anyone who may have any information about this robbery is asked to contact detectives at Troop 2 at 302.834.2630 ext. 218 or Delaware Crime Stoppers at 1.800.TIP.3333.