Twenty-eight-year-old Alan Womack Jr. was shot outside the LA Fitness in the busy Village at Valley Forge complex around 10 p.m. Friday.
Police say the shooting happened after an argument on the basketball court, and investigators say both men fired guns.
Sources say the other shooter was questioned by police and released. Investigators are looking into the possibility of the homicide being justified as self-defense.
Womack lived near the LA Fitness and was originally from Philadelphia. He played basketball at Fisher College in Boston.