It happened at the Fulton Bank in the 3900 block of Kirkwood Highway and Woodhaven Drive around 9:00 a.m. Friday.
Police say the robber displayed a hammer and demanded cash.
After getting what he thought was money he left.
When police later arrived they followed the man's footprints in the snow, which led them to the exploded dye pack.
The suspect has not been located and it still on the loose.
He is described as a white male, 35-40 years of age with a medium skin tone, 5'09" tall and stocky build. He was last scene wearing a red, white and dark colored jacket, gray hooded sweatshirt or jacket, and dark pants. He was armed with an unknown club style weapon.