Nassau County police are searching for an armed man wearing a Halloween mask who robbed a Hicksville gasoline station early Saturday.

Police said a man went to the BP Gas station at 325 Jerusalem Ave. at about 2:30 a.m. and showed the a 29-year-old clerk a black handgun while demanding cash from the store’s register.

The gunman took all the cash from the drawer and put it in a black plastic bag before running north on Jerusalem Avenue, police said.

The clerk, who was not injured, said the assailant was wearing a Halloween Joker mask.

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The gunman also was described as wearing a black hooded sweatshirt, baggy jeans and white sneakers.

Police are asking anyone with information to call Nassau County Crime Stoppers at 800-244-TIPS. Callers will be kept anonymous.