JACKSONVILLE, Fla. -

A student at Arlington Elementary School was arrested Wednesday with a semi-automatic handgun in his backpack as a group of students was preparing to leave on a field trip.

According to the Jacksonville Sheriff's Office, the boy's older brother got the .25-caliber Raven Arms handgun from a friend on Tuesday and the younger brother brought it to school Wednesday to show off.  The gun was not loaded.

Officers interviewed both boys and their mother, who was called to the school.

The 12-year-old caught with the gun said neither he nor his brother was bullied.  Their mother said both boys have muscular dystrophy and have some deficiencies understanding things.

The boy, whose name is not being used because of his age, was charged with possession of a firearm on school property and possession of a firearm by a minor and placed in the youth detention center.