They are looking for a woman in her 20s, about 5-foot, 5-inches tall.
According to public safety spokesman Steve McCausland, the woman confronted the manager of the KeyBank on Main Street in Bethel armed with a small handgun.
She walked up to the manager just as she was arriving for work at the front door of the branch at about 8:20am.
The woman was reportedly wearing a multi-colored scarf over her face, a maroon knit cap, a white T-shirt, tan capri pants, green gloves, wearing white crocs on her feet and carrying a canvas backpack.
The manager used her own ATM card to make a withdrawal from a machine in the bank’s entryway, and gave the cash to the robber.
Police are not saying how much money was taken.