MINNEAPOLIS (WCCO) – Officials at a Twin Cities high school say an inoperable gun was found Monday in a backpack and an individual who did not attend classes there was taken into custody.

In a letter to parents, Armstrong High School says that students reported Monday that a non-Armstrong student was inside of the building.

School officials found the individual during a routine building check, and upon searching their backpack found an inoperable firearm.

Plymouth police officers responded and took the individual into custody.

No students were hurt, the school says.

Plymouth police are investigating the incident.