A group of five people has been robbing teenagers around Prospect Park, police said.
The robberies happened between April 25 and May 2, the NYPD said.
In the first robbery, a 16-year-old boy lost $8 and wasn't hurt, police said.
But the second time, a 13-year-old boy was robbed of his iPhone and punched in the face, police said.
Both of the first two robberies happened near West Lake Drive and West Drive in the park.
In the third attack, at Prospect Park West and 9th Street, a 17-year-old boy was punched in the face and robbed of his iPhone and backpack containing a MacBook computer and OontZ speaker, plus his school work, police said.
Police released a photo of one of the five suspects.
Anyone with information is asked to call the NYPD's Crime Stoppers Hotline at 1-800-577-TIPS (8477).