PARK HALL, Md. (AP) — Police in Maryland say they've arrested an 8-year-old boy after a loaded gun was found in his book bag in his elementary school.

The Washington Post reported that it happened Wednesday at Park Hall Elementary School in St. Mary's County. That's the county where just last month, authorities said a high school boy fatally shot a girl and then killed himself as a school security officer confronted him.

The Naval Criminal Investigative Service will dig into how this elementary schooler got access to the semi-automatic handgun. School officials found it after another student alerted a teacher. Police believe he brought it from home in an off-base military housing community. They say both of his parents are on active duty.

The boy has been charged as a juvenile with weapons offenses.