Authorities were called to Parkway West High School, 4725 Fairmount Avenue, around 2:35 p.m. on May 26 for a reported incident, the department told Daily Voice.
The victim, a 17-year-old boy, was found to have one stab wound to the "right buttock," police said. Officers took him to Presbyterian Hospital where he was placed in stable condition, they added.
No arrests had been made as of Friday evening, and no weapon was recovered from the scene, according to the department.
Click here to follow Daily Voice Allentown and receive free news updates.