Little Rock police say witnesses reported seeing a 5th grader put a weapon put an unloaded handgun in his little brothers book-bag at Watson Intermediate Elementary school.
Police say the 5th grader showed it to someone on the school bus and threatened to hurt them if they told anyone.
The child did tell someone and authorities were called in and found the gun -- which ended up belonging to the child's grandfather - who works for the Little Rock Police Department.
According to police, the children visited their grandfather on Tuesday, and even though the gun was put away, they found it and took it.
Police say the grandfather is a 21 year veteran of the Little Rock Police Department.
"Our officer is not being investigated. He had the weapon secured in his bedroom, his grandson's just found it. As you can imagine he is very upset about it, that his grandsons would do that," said Lt. Terry Hastings.
Police say the 5th grader, who is 11-years-old, is being charged with being a minor in possession of a firearm at school and terroristic threatening.
The child's brother, an eight year old, is also being held responsible but is too young to face charges.