CHICAGO (CBS) — A 12-year-old boy brought an unloaded gun to his South Side elementary school on Monday because he said he was being bullied.

A security guard at Schmid Elementary School, 9755 S. Greenwood Ave., discovered the weapon, police said.

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The boy was arrested around midday and was charged as a juvenile with unlawful use of a weapon, police said.

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The Chicago Tribune reported that the gun was a .38 special, and that the serial number had been defaced.

Police News Affairs told CBS 2 that they could not provide information on the weapon.

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Jessica Wilson, who is a grandparent of another student told CBS 2’s Susanna Song: “I know Schmid. They have a lot of security, and the principal is on top of things.”