It happened on a platform for the Market-Frankford Line at Market and 15th streets around 3:30 p.m.
Police say a brief fight escalated to shots being fired.
A 23-year-old man was shot twice during the incident, authorities say. He was transported to Jefferson Hospital and is listed in stable condition.
Authorities also say he is being held as a prisoner at this time.
According to police, a suspect is in custody and a weapon was recovered at the scene.
Investigators did not release any further details on this incident. Anyone with information is asked to contact the police.
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