Police say another boy already in custody in Friday's shooting at the Delaware Valley Charter High School in north Philadelphia has not been charged yet.
Police aren't identifying either boy because of their age. They say they contacted the second suspect's parents before the 17-year-old turned himself in Saturday afternoon.
Police say two students were wounded in what may have been an accidental shooting.
Authorities say a girl was treated and released after the bullet struck her a bicep. The same bullet then hit a 17-year-old male student who remained hospitalized in stable condition.