FISTS FLEW FIRST

Vid of ‘haymakers’ at cop before fatal shoot

Surveillance video shows a roadrage motorist “punching the s--t” out of an off-duty cop through a car window before the officer fatally shot him, the owner of a nearby store said Wednesday.

The proprietor of Touch of Glass on Atlantic Avenue in Brooklyn said he plans to give his store video to the NYPD. It shows 37-year-old Delrawn Small (inset) get out of his car at a traffic light at the intersection of Atlantic Avenue and Bradford Street and charge Officer Wayne Isaacs’ car — two vehicles ahead — the store owner said. Small thought Isaacs had cut him off.

Small’s girlfriend, Zaquanna Albert, 35, can be seen trying to hold him back, but he could not be restrained as their 5-month-old son and one of Albert’s teenage daugh- ters sat in the car.

Small pummeled Isaacs, 37, through the cop’s open driver’s side window with “big haymaker” punches before a flash of gunfire is seen in the video, said the business owner.

“The video shows the guy coming out of his f--king car, running up to [the cop’s] car, going in the driver’s side window and just punching the s--t of this poor cop. Then, all of a sudden, you see sparks,” the owner said, adding that the next image is of Small hitting the pavement.

He added that Small “was waling on [Isaacs’] face, like ‘pow, pow!’ He was looking to knock this guy out, punching and punching. Maybe four punches. It was big haymakers.”

Small’s girlfriend initially told police investigators that Isaacs exited his car and opened fire on Small, but police sources rejected that narrative.

Isaacs, who was heading home after a 4 p.m.-to-midnight shift in the 79th Precinct in Bedford-Stuyvesant, pulled his service weapon from underneath his white T-shirt and blasted Small once in the head and once in the chest after the pummeling, sources said.

Small, an ex-con who has a lengthy rap sheet with 19 prior arrests, died at the scene.

Police sources told The Post that investigators have already recovered surveillance footage from a different, less visible vantage point.

Family members of the slain dad told The Post Tuesday that if Isaacs, a three-year veteran, is not charged for the killing of Small, they’ll “hunt him down” themselves.

At a vigil for Small on Atlantic Avenue Wednesday night, the slain man’s brother said it didn’t matter if Small threw the first punch.

“At the end of the day, all that matters to me is that he got shot by a cop for no reason,” Victor Dempsey said.

The NYPD is investigating the fatal shooting along with the state Attorney General’s Office.