The incident happened just after 6 p.m. on the 1300 block of N. 10th Street.
Police say the teens, two brothers and a friend, were eating pizza outside when a car pulled up and opened fire.
A total of 31 shell casings were found at the scene, according to police.
An elderly couple's vehicle was also hit by gunfire while sitting inside their car near the scene. Officials say, however, the couple was unhurt.
Police say a 15-year-old male was shot twice in the right thigh.
A second victim, a 16-year-old male, was shot once in the abdomen and once in the buttocks.
A third victim, a 17-year-old male, was shot once in the left shin and once in the left thigh.
All three victims were transported by police to Temple University Hospital and listed in stable condition.
There have been no weapons recovered at this time.
So far, no arrests have been made.