A grandmother shot and killed her grandchild’s mother before fatally turning the gun on herself on the Upper East Side Friday morning, authorities said.

The shooting happened on East 88th Street, between York and East End avenues, just before 9 a.m., less than a block away from Gracie Mansion, NYPD Chief of Detectives Joseph Kenny said at a press conference.  

Upper East Side resident Marisa Galloway, 45, was putting a stroller in the trunk of a car after placing her young child in the backseat when she was shot in the head, and then again in the back, police said.

Surveillance footage shows Kathleen Leigh, 65, of Chicago, Illinois, firing the weapon at Galloway before shooting herself in the head, Kenny said.

Leigh was pronounced dead at the scene, and Galloway was pronounced dead at a nearby hospital, according to Kenny.

The child was physically unharmed, the NYPD said.

Kenny said police believe the shooting stemmed from an ongoing custody dispute between the two women and a third person.

Five domestic incident reports and two complaint reports had been filed with the NYPD previously, none of which led to an arrest, he said.

Police believe Leigh, a retired Cook County probation officer, had been living in the city with family members for the past three years, Kenny said.

Officers found a loaded 9 mm gun on the sidewalk near the car and a second gun in Leigh’s tote bag, he added. An investigation is ongoing.