Katherine Carter, a prosecutor's office spokeswoman, would not comment on a motive. She said there was no information on whether the victim - another 17-year-old from East Orange who was struck in the arm - knows the suspect.
The gunman, who was shot once in the torso, underwent surgery at University Hospital in Newark. The other teen was taken to Clara Mass Medical Center in Newark.
Both remained hospitalized Sunday, but were expected to fully recover.