It happened just past 4:30 a.m. Monday at the store on the 4700 block of Mascher Street.
Police say suspect entered the store and pointed a handgun at the clerk behind the counter.
Click here to watch the surveillance video
The gunman stated he would kill a customer who was shopping insdie if his demands for cash were not met.
The clerk then placed an unknown amount of cash into a 7-Eleven bag and the robber fled the scene.
No one was injured in the incident.
Police describe the suspect as a black male with a stocky build, 185-205lbs. and 5'10 tall. He was wearing a black hat, black rag covering his face, gray hooded sweatshirt and black jeans.
If you recognize this suspect, call police at 215.686.TIPS (8477) or text a tip to PPD TIP (773847).