Shocking new video shows the moment a gunman opens fire in an unlicensed Bronx bar — killing a man during a squabble over the bathroom, cops said.

The fatal encounter happened just before 4 a.m. May 9 inside a crowded nightclub at 4555 3rd Ave. in Belmont, according to cops.

The two men were waiting to use the bathroom when the 30-year-old victim, identified by cops as Shamar Watt, let two women cut in line for the single unisex bathroom.

After the women come out, the two argue who’s next, cops said.

Moments later, the gunman walks up to Watt on the dance floor and fires twice at “near-point-blank range,” striking him in the head, according to police.

Watt died two days later at Saint Barnabas Hospital, police said.

The NYPD released the video Friday to help track down the unknown gunman.

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