Two women were shot to death in a murder-suicide on the Upper East Side of Manhattan on Friday morning, according to the police.

Officers responded to a 911 call around 8:55 a.m. about two women who had been shot near a white Honda Civic outside an apartment building at 519 East 88th Street, just a half block from Gracie Mansion, the official residence of the New York City mayor.

One of the women, identified by the police as Kathleen Leigh, 65, approached the second woman, identified as Marisa Galloway, 45, shooting her in the head and lower back. Ms. Leigh then shot herself in the head, the police said.

Ms. Leigh was pronounced dead at the scene, the police said. Ms. Galloway was taken to Weill Cornell Medical Center, where she later died.

Joseph Kenny, the chief of detectives for the Police Department, said the shooting was related to an ongoing child-custody dispute.

In a news conference on Friday, the police said they had a video showing Ms. Galloway putting her 1-year-old daughter into a car seat in the back of the Honda just before the shooting. Then, as Ms. Galloway walked to the rear of the car to put a stroller in the trunk, Ms. Leigh approached and shot her in the head, the police said. Ms. Leigh can then be seen shooting Ms. Galloway in the lower back.