Wort Whipple, 14, was fatally shot in the 5200 block of Market Street on the platform for the Market-Frankford Line train just after 2 p.m.
Police said he was shot in the chest and arm.
READ | 14-year-old shot, killed on SEPTA platform in Philadelphia
He was taken to Penn Presbyterian Medical Center where he died a short time later.
Sources told Action News the shooting was instigated by an altercation between the victim and the suspect.
They say it turned physical when the teen hit the male suspect.
That's when the suspect allegedly pulled out a gun and fired at least two shots, fatally wounding the teen. The man then immediately fled the scene.
Sources also confirmed the suspect likely tried to hide evidence of the crime by burning his clothes behind a laundromat near the scene.
In photos released by police, the suspect is seen wearing all black clothing, a black face mask, and black and white shoes.
Anyone with information about the shooting or the suspect is asked to call SEPTA police at 215-580-8111 or Philadelphia police at 215-686-TIPS (8477).