(CNN) A Pennsylvania school district has a different solution for tackling intruders: rocks.

Buckets full of river stones have been placed in all classrooms at the Blue Mountain School District in Schuylkill County, Superintendent David Helsel said.

If students at the rural school district can't evacuate during a shooting, they don't have to sit and wait.

"Protocol has been that students lie down, under desks and basically become passive targets on our classrooms," Helsel said. "We decided to empower our students with tools of self-defense if needed."

In a video posted online, the superintendent said the district decided to bring rocks to the classrooms after staff members took the active shooter response training, ALICE -- alert, lockdown, inform, counter and evacuate.

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