NEW YORK — An off-duty NYPD officer involved in a deadly shooting on July 4th has been placed on modified duty.

Family members said 37-year-old Delrawn Small was with his girlfriend and children celebrating the holiday when they stopped at a friend’s barber shop on Atlantic Avenue in Brooklyn.

At some point just after midnight, police said Small and the officer, who was driving his personal vehicle, were involved in a traffic dispute.

When both cars stopped at a red light, police said Small got out of his vehicle and punched the officer repeatedly in the head through an open window.

That’s when police said the officer pulled out his service weapon and shot three times, killing Small, according to the police account. The officer — identified as Wayne Isaacs — was treated for bumps and bruises to the face and head at Jamaica Hospital Center.

But as WCBS 880’s Alex Silverman reported, surveillance video shows Small getting shot almost instantly after reaching Isaacs’ car.

Police Commissioner Bill Bratton said that the cop had just finished a shift and was likely headed home at the time of the incident.

“It’s much, much too early to draw any conclusions at this time,” Bratton said. “It is a protocol that our Force Investigation Division will do a very comprehensive initial investigation. We’re gathering a lot of video from the area, cameras that we were able to identify. We have talked with the officer.”

New York State Attorney General Eric Schneiderman is leading the investigation in the case – in what amounts to standard protocol since Small was unarmed.

Small’s family held a news conference and is demanding a full investigation.

“His wife was in the car with him. His two kids were there,” said Victor Dempsey, the victim’s brother. “They were going to see fireworks up by whatever park is in the neighborhood.

“It has to stop. It’s not right that they just get a gun and a badge and they can do what they want to do,” Dempsey added.

Meanwhile, police said 12 cars had their tires slashed Sunday morning outside the 79th Precinct station where Officer Isaacs works.

“Doesn’t surprise me that someone targeted police officers’ cars,” said Lou Turco, who heads the Lieutenants’ Union. “It’s not surprising, unfortunately.”

Isaacs, a three-year veteran of the force, has been placed on desk duty and has been stripped of his badge and gun.

Attorney General Eric Schneiderman is investigating.