She was rushed to Long Island College Hospital, where she was pronounced dead.
The victim lived in the area of the shooting, which occurred near the Gowanus Houses in Brooklyn, a city-run apartment complex. Residents of the complex said they heard the gunfire.
"It's a life-altering experience," said Jason Torres, who rushed outside after the shooting and saw the body. "It makes you think about life. I got kids, you know. And I just thought about them. I don't want them to be out here, at that age. It makes you think you want to keep them in the house, and you know they're teenagers, they want to be outside. But it's dangerous."
The gunman, who witnesses only described as wearing a red shirt, fled the scene.
No arrests were immediately made.