The victim, identified as Nichelle Thomas, 51, was shot just before 1 p.m. at Fourth Avenue and St. Marks Place in Park Slope.
Footage obtained by The Post showed Thomas approaching a bodega at the corner of St. Marks Place — apparently unaware her ex was about to launch an attack.
As Thomas went to open the door, 38-year-old Latisha Bell allegedly sprinted up and pulled a gun. Bell then allegedly shot Thomas point-blank in the back of the head and fled.
The chilling nine-second video ends with the victim crumbling to the ground.
She was rushed to a hospital where she died, police said.
The two women used to be in a relationship, police sources said. It wasn’t immediately clear when they broke up.
Police didn’t immediately provide a motive for the shooting. But investigators are looking into the possibility that the fatal encounter was sparked by a lover’s quarrel, according to law enforcement sources.
Witnesses in the normally safe neighborhood were shocked over the daylight violence.
“I’ve been working here for 12 years and I’ve never seen anything like this,” said bodega cashier Mohammed Ali.
“It’s scary. If the bullet hadn’t hit her, I might have been the one hit,” said Ali, 57.
Ali said he heard one shot, which he knew was from a gun.
He said he then ran outside and saw “a lady lying face-up on the sidewalk and above her eyes was a hole with blood coming out.”
Bell with her lawyer in tow surrendered to cops at the 78th Precinct station house hours later. She was later charged with murder and criminal possession of a weapon.
The shooting was the first recorded in the neighborhood this year, according to NYPD data, and comes as the Big Apple experiences a nearly yearlong surge of gun violence.
The Mayor’s office on Tuesday announced an initiative to curb gunplay during the summer months when cities historically see an uptick — but the plan mirrored the failed policing strategy from last year.
Andrea Iglesias, 52, told The Post as he looked on the latest act of bloodshed, “It’s unreal what’s happening in this city.
“This is a good area. People don’t get shot here, especially in broad daylight on a busy intersection. There’s so little enforcement anymore, people feel emboldened.”
This story first appeared in the New York Post.