Sources tell Action News the alleged shooter is facing murder and attempted murder charges.
The shooting happened on February 23.
The victim, Embaba Mengesteabe, was with her brother at the time.
Police believe her brother was the intended target.
An arrest warrant has been issued for a second suspect in this case, 18 -year-old Ousmane Fine.
The news of the arrest came in a statement from Police Commissioner Danielle Outlaw, who decried recent violence affecting juveniles in the city.
Outlaw said she was "saddened and outraged" by cases such as the death of 15-year-old Antonio Walker Jr., who was found with multiple gunshot wounds Tuesday night in the Kingsessing neighborhood of southwest Philadelphia.
Police say Walker's killing appears to be a random act of violence.
At 3:30 a.m. Wednesday, she said, there was a shooting involving another 15-year-old in the Holmesburg neighborhood of northeast Philadelphia. He is expected to survive, but Outlaw said "we cannot ignore the physical and emotional trauma that this juvenile and his family will have to endure for some time."
"I implore the community to be proactive and remain vigilant," Outlaw said. "The duty to protect these children belongs to all of us." She said police are doing everything they can to stem the violence, "working with community partners to stay ahead of violent showdowns and intervene wherever possible."