Surveillance video captured the suspect entering the 11th and Tree Grocery Store on the 2200 block of South 11th Street shortly after noon on October 4.
Click here to watch the surveillance video
Police say the suspect approached a 39-year-old female employee behind the counter and demanded money.
When the clerk told the suspect there wasn't any money, the suspect said he was armed with a handgun and threatened to harm her and her children.
The suspect then reached inside the cashier booth and grabbed several Pennsylvania Lottery scratch off tickets before fleeing north on 11th Street towards Jackson Street.
Police describe the suspect as a white male with a beard. He was wearing a Black hooded jacket, red and white pants, and sunglasses.
Anyone with information is asked to call police at 215.686.TIPS (8477) or text a tip to PPD TIP (773847).