A knife-wielding robber forced the employee of a Baldwin Dairy Barn to open the cash register, then stole money and fled, but not before forcing the worker into the store bathroom, police said.
The robbery took place at the store on Grand Avenue just after 12:30 p.m. Sunday.
Nassau County police said the employee, a 20-year-old man, was not injured.
Police did not say how much money was stolen.
Police said the robber was believed to be in his late teens, between 5-foot-8 and 5-foot-10 and about 150 pounds.
He was wearing black sneakers, black cargo pants with zippered pockets, a black shirt, black baseball cap, black bandanna covering his face -- and a white belt with a diamond-shaped emblem on it.
Police are asking anyone with information regarding the robbery to call Crime Stoppers at 800-244-TIPS. All calls will remain confidential.