The man entered the Shell gas station at 3800 Kennett Pike about 2:47 p.m. and demanded money from a cashier while displaying a knife, Sgt. Paul Shavack said.
The worker complied and turned over an undisclosed amount of cash to the robber, who fled on foot, Shavack said. No injuries were reported.
The suspect was described as white, 20 to 25 years old, 5 feet 5 inches to 5 feet 7 inches tall and weighing about 150 pounds. He was last seen wearing a shirt, pair of pants and bandana--which was used to hide his identity--that were described as dark.
Surveillance photos of the suspect were not available for release Thursday night, Shavack said.
Anyone with information can call the Troop 2 Robbery Unit at (302) 834-2630 ext. 6 or by using the Delaware State Police Mobile Crime Tip application.
Tips can also be submitted to Delaware CrimeStoppers at 1 (800) TIP-3333, online at www.tipsubmit.com, or by sending an anonymous tip by text to 274637 (CRIMES) using the keyword "DSP."
This material may not be published, broadcast, rewritten, or redistributed.