ST. PAUL, Minn. (AP/WCCO) — Police in St. Paul are investigating how a loaded handgun ended up in the backpack of an elementary school student.

Sgt. Mike Ernster says the 8-year-old girl put her backpack on the floor at John A. Johnson Achievement Plus Elementary School Monday and heard a thud. Ernster says she opened the backpack and found the gun, then told her teacher about it. The girl wasn’t sure how the gun ended up in her bag.

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Police responded and secured the semiautomatic handgun. The magazine of the gun was loaded, but the chamber was empty.

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The child was released to the mother, who did admit the gun was hers.

The investigation into how the gun ended up in the child’s backpack is ongoing.

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(© Copyright 2019 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.)