A Brooklyn park turned bloody Monday afternoon when bullets started flying, striking five teenage boys, police sources said.

The victims were inside Harry Maze Park on East 56th Street in East Flatbush when someone took a bag from a teen there and he called his friend, who came over and started firing just before 5 p.m., sources said.

The victims — who are all expected to survive – are between 15 and 17 years old. They were taken to Kings County Hospital.

The shooter, who is believed to be between 17 to 20 years old, fled on foot.

He was last seen wearing a red shirt, black jeans and carrying a bookbag with the letters “MCM” on it, cops said.