It happened at the TD Bank at 701 East Street Road just before 5:00 p.m. Wednesday.
Officials say a man reportedly handed the teller a note demanding money.
After getting an undetermined amount of money, the man fled in a dark colored Honda Pilot.
The suspect is described as a white male, late 40s to early 50s, 6' tall, heavy build, with reddish blond hair with a beard.
He was wearing a red and white Phillies hat, a gray hooded sweatshirt with a possible "Nike" emblem, shorts and sneakers.
No injuries were reported.
Anyone with information is asked to call the Lower Southampton Police Department at 215-357-1234.