The incident happened just after 3:30 p.m. near the intersection of Mascher Street and Duncannon Avenue.
Police say 16-year-old Tyler Perri was walking across Duncannon Avenue after school from Olney Charter High School.
"I just got a phone call from my son's school that he was being rushed to St. Christopher's Hospital (for Children)," said Perri's mother Rosemarie Molina.
He was taken to St. Christopher's Hospital for Children and listed in severe condition.
"He can't do nothing but scream. They have to keep giving him medicine so he can stay calm," said Molina.
Molina says she learned about what happened and the long road ahead he'll have to undertake.
Perri's leg is badly broken, and his right arm is severely injured.
To make matters worse, Perri suffers from hypoplastic left heart syndrome and scoliosis. So getting back to normal for him will be that much more difficult.
"He's had three open-heart surgeries. I need my son to be okay," she said. "He's 16 years old, the size of a 9-year-old. My son doesn't go out looking for trouble."
Molina has a message for the driver to turn themselves in after hitting and leaving Perri at the scene.
Police have a description of the car they want everyone to look out for.
It's a small silver-colored four-door with previous right side damage.
Both right side windows are also covered by plastic, police say.
Anyone with any information is asked to call police at 215-686-TIPS.