The drive-by shooting happened around 6:3o p.m. outside the Ford PAL Ford Recreation Center in the 2000 block of South 7th Street.
According to Chief Inspector Scott Small, the gunman, who was a passenger in a silver vehicle, fired five shots at the teenagers.
"Based on ballistic evidence, we know at least five shots were fired from a semi-automatic weapon. We found five spent shell casings on the highway at 7th and Snyder," Small said.
Police said a 17-year-old was shot in the foot and a 19-year-old was shot once in each leg.
Investigators said the teens were shot on the block after playing basketball with police at the PAL Center, which is where officers run educational programs for youth.
"They were able to verify that these two teenagers were in the PAL Center playing basketball just a minute before being shot," said Small.
The teens are listed in stable condition at an area hospital.
No arrests have been made.
Anyone with any information is asked to call police at 215-686-TIPS.