Police said the man walked into the bank on 8 Little East Neck Rd., handed a note to the teller demanding cash and acted as though he was armed.
The teller handed over an undisclosed amount of money and the suspect left, running north through the parking lot.
He is described as in his mid-20s, 6-feet-2, with a slim to medium build, unshaven face and dark hair. He was wearing a black hooded sweatshirt, jeans and black gloves.
Anyone with information about this case is asked to call 800-220-8477. Callers will remain anonymous.