There were four employees and one customer in the bank at the time, Nassau County police said. No one was injured.
Police said the robber, wearing a black and green jacket and a black knit hat, walked into the bank at 6:51 p.m. -- and "threatened to shoot the female teller." Police said the robber did not display a weapon.
The 30-year-old teller complied with the robbery demand, police said, and handed over an undisclosed amount of cash.
The robber then fled north on Great Neck Road.