Police say someone shot an 18-year-old man once in the chest at 5:48 p.m. Monday at 22nd and Huntingdon streets.
The teen was transported by medics to Temple University Hospital where he was pronounced dead.
Officials say the playground was full of people. There were children on the pick up basketball court and football practice field.
Chief Inspector Scott Small said, "...at least 25 young children with their parents as well as young adults and teenagers were in the playground."
Witnesses have described the suspect as a 20-year-old male, 5'6" tall and 200 pounds. He was wearing a multi-colored sweater, sneakers and blue jeans.
He was last seen fleeing on a bike westbound on the 2200 block of Huntingdon.
Authorities have not released the victim's identity and the search continues for the suspect.