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Middletown police officers were dressed in full gear as they entered the building, where Middletown City Manager Doug Adkins played the role of a shooter.
Used in recent years as a middle school, the old Middletown High School first opened to students in 1923. It was the oldest school in Butler County until it was closed for its final school year earlier this month.
It is set to demolished in a few months, according to school officials.
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Watch the video above to see the active shooter training in progress.
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