FRESNO, Calif. (AP) — An elementary school superintendent in Central California says he allowed a janitor to wear a mask and carry a fake gun during an active shooter drill to “make sure this was realistic.”

A teacher told KSEE-TV that the drill, which happened at Raisin City Elementary School before the summer break, went too far.

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Kim Copper said the masked gunman pounded on her classroom door and tried to open it as she huddled in a corner with terrified students.

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School Superintendent Juan Sandoval admitted teachers and students were not told about the janitor’s role. He said active shooter drills have become routine and he wanted students to understand the gravity of the situation.

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A school board official told the station the school will improve its active shooter training procedure.