Nassau County police say Enley Ball of Tobyhanna, Pa., entered a TD Bank in Franklin Square on Thursday, displayed a handgun and demanded money.
They say the 33-year-old suspect then fled with an undetermined amount of cash.
Police arrested him a short time later.
Ball was charged with robbery, criminal use of a firearm and criminal possession of a weapon.
It was not immediately known if he had a lawyer.
Get Eyewitness News Delivered