A man held up the Turkey Hill convenience store in Ronks early Friday morning, East Lampeter Township police said.
The robber displayed a weapon, but police declined to disclose what kind, and escaped with an amount of cash, which also was not disclosed.
The man fled on foot after the robbery, which happened about 12:15 a.m. at the store at Route 30 East and Ronks Road. The clerk was not injured.
The robber was described as a black male, about 30 to 39 years old, about 5 feet 10 inches tall and weighing about 175 pounds.
He was wearing a red hooded sweatshirt with USC on the front and a red Philadelphia Phillies baseball hat. He also was wearing dark-colored pants, white sneakers and a black knit mask covering most of his face.
Anyone with information about the robbery is asked to call Lt. Robin Weaver at 291-4676.