A man wearing a mask and carrying a gun robbed a Uniondale 7-Eleven store early Wednesday and made off with an undetermined amount of cash, Nassau County police said.

No customers were present and no injuries were reported, police said.

At 3:35 a.m. the man, armed with a short rifle or shotgun, entered the store on Jerusalem Avenue and demanded money from the clerk, police said.

After the clerk opened the register, the man, wearing a cloth mask, reached in and took cash, then fled on foot, first heading east on Jerusalem, then south onto Amsterdam Avenue, police said.

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Police described the man as 6-foot-2, about 225 pounds, and wearing “tan khaki baggy pants, black coat with hood, and dark shoes.”

First squad detectives are asking anyone with information to call Nassau Crime Stoppers at 1-800-244-TIPS. All calls will be kept confidential.