The incident happened Wednesday night around 7 p.m. inside the Amber Mini Market on the 4200 block of Nielson Street.
Surveillance video shows the suspect walk in and immediately point a handgun at the employee behind the counter.
After the employee ran safely to the back of the store, the suspect then went behind the counter himself and grabbed $300 cash along with several packs of cigarettes before fleeing the scene.
Anyone with information is asked to call East Detectives at 215.686.TIPS (8477) or text a tip to PPD TIP (773847).
All tips will remain anonymous.