Shocking video shows the moment a young gunman shoots a man on a Citi Bike at point-blank range in Brooklyn.

The clip of the Wednesday slaying at the corner of Clarkson Avenue and East 53rd Street in East Flatbush first shows the suspect standing outside a deli, talking on the phone around 2:20 p.m.

The footage, released by cops late Thursday, then cuts to victim Pierrot Simeon, 21 — rolling up to the store on the bike and stopping to apparently speak with the suspect, who whips out a gun from a fanny pack slung over his shoulder and opens fire.

Simeon collapses off his bike, and the suspect ditches the gun and runs off, the footage shows.

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