The robbery happened around 2:30 p.m. at the branch located at 2516 Welsh Road.
The FBI says the man gave a threatening demand note to the teller then, after obtaining an undisclosed amount of cash, fled the bank on foot.
The suspect is described as a black man in his 30's, about 6'3" tall with a large build. He had a thin mustache and a goatee and wore a black t-shirt and brown cargo pants.
The man was also carrying a backpack or shoulder bag and wore some kind of device on his forehead. The FBI says it may have been some kind of flashlight.
He was not, however, wearing a mask.
Anyone with information is asked to call the FBI at 215-418-4000.
