It happened around 3:15 Sunday afternoon by Estevez Grocery on the 400 block of East Washington Lane.
A witness tells Action News, "Three boys walking up, one turns around, pulls out a gun and boom."
Police say a fight between two groups of teens led to the shooting.
Sources tell Action News that these rival groups have been fighting for years, usually with their fists but now the violence escalated to gunfire.
"One turned around, pulled out a gun and shot him once below the heart," said the witness.
According to police, the victim was shot in his side and was driven to Albert Einstein Medical Center in critical condition.
Two hours later, just blocks away, an officer spotted two juveniles who fit the description of the suspects and chased after them.
The two teens were caught and taken into custody for questioning.
Police say they believe the two were involved in the fight but they are not sure who actually pulled the trigger.
Authorities are still looking for more suspects and are hoping surveillance video from the grocery store will help piece things together.