Maximillian Reyes managed to dial 911 after he was shot in the abdomen at Ammann Park off Teaneck and Fort Lee roads around 4 p.m., responders said.
Reyes was rushed to the trauma unit at Hackensack University Medical Center, where he was pronounced dead, Bergen County Prosecutor Mark Musella said.
No other injuries were immediately reported.
A Bergen County K-9 unit was summoned to help search for the shooter.
No arrests had been announced as of early Sunday afternoon.
Anyone who might have witnessed the shooting or has information that can help authorities identify the shooter is asked to contact the prosecutor's tips line at (201) 226-5532 or Teaneck police: (201) 837-2600.
Click here to follow Daily Voice Ridgewood and receive free news updates.