It happened just after 9 p.m. in the 4500 block of North 17th Street at the Stenton Park Recreation Center.
According to Philadelphia Police Chief Inspector Scott Small, the male victim, believed to be in his 20s, was found lying in a path near the rec center.
Chopper 6 was overhead as officers cordoned off an area of the park.
Police say the victim was rushed to an area hospital where he was placed in extremely critical condition.
No arrests have been made.
Anyone with information is asked to call police at 215-686-TIPS.