Officers responded at approximately 8:54 p.m. to 900 block of East 17th Street for the report of a shooting behind the Swartz Center Gymnasium.
Arriving officers found the 19-year-old student lying on the ground having been shot in the head and left shoulder.
Paramedics transported the victim to Crozer-Chester Medical Center where he remains in serious condition.
Chester police say the student was sitting inside a vehicle after playing a game of basketball when the shooter approached and opened fire.
Police say the shooting does not appear to be a random act.
The suspect is described as a male wearing dark sweat pants with a white stripe and a blue jean jacket. He remains at large and was last seen running off campus towards the Sun Hill section of the city.
Anyone with information is asked to contact investigators at 610-447-7813.