An armed serial robber struck again by hitting an Elmont gas station, the seventh he's held up in the past month, Nassau police said Tuesday.

Detectives say they want the public's help to nab the suspect, who conceals a black, semiautomatic handgun with his T-shirt or a cloth during the robberies.

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In his latest robbery, the gunman took off with money from a 76 Gas station on Linden Boulevard in Elmont about 8:45 p.m. Monday, police said.

The man, who appears to be in his 20s, commits the robberies at night, police said. He demands money and then runs away, police said.

He is about 5 feet 8 inches tall, with a medium build, dark complexion and facial hair, police said.

Robbery detectives asked anyone with information to call 516-573-8040 and refer to robbery squad pattern No. 09-2015.