The teen was shot at 7:30 p.m. on the sidewalk at Penn and Bridge streets just feet from the Frankford Playground.
Authorities say at least 20 people were present at the playground when gunfire erupted.
A SEPTA bus driver witnessed the shooting and is speaking with police. Investigators are also pulling video from the bus and a nearby SEPTA depot.
Police have not released any information about a suspect.
Anyone with information is asked to call 215-686-TIPS.