There was increased security at North Penn High School in Montgomery County after a 16-year-old student was arrested with a weapon on Tuesday.
The university says two current students and a former student were involved in the incident.
A Temple University student has been charged with allegedly impersonating an ICE officer on campus in North Philadelphia.
The shootings resulted in damaged vehicles and homes, and a woman was injured.
The security office detained the 17-year-old student and the magazine was recovered.
Police have arrested and charged a suspect on murder charges in connection with the shootings of two people who were found dead in a dorm room last week at the University of Colorado-Colorado Springs.