Duluth East High School went into lockdown and a student was arrested after police found a loaded magazine in his locker.
The 17-year-old student was taken into custody, with the school going into lockdown at around 11:20 a.m. Tuesday.
The student's locker had been searched due to school staff finding a vape pen belonging to him, and inside the locker they found a loaded magazine with 9mm ammunition inside a backpack.
It prompted a police operation at the school, with the student located and detained while officers and a K9 searched for any accompanying gun, but none was found.
The lockdown ended around 1 p.m.
As well as facing charges for possession of ammunition by a prohibited person, the student is also set to face discipline in school, with school officials saying a suspension and disciplinary hearing is possible.