The gun was fired by a student who pulled it on two other students.
The injured boy and girl, each 15, were transported in stable condition after being shot in the arm just before 3:30 p.m., Philadelphia police Lt. John Stanford said.
The students were among about seven in the Delaware Valley Charter High School gym at that time — some playing basketball, others in one corner — according to city police Commissioner Charles Ramsey.
“The suspect is part of that group,” Ramsey said.
The suspect is in custody, and two others are being sought.