PHILADELPHIA (February 8, 2013)--A 7-year-old boy alerted a teacher after he found a loaded gun in his backpack at a Philadelphia elementary school, police said.

The boy found the gun at around 4 p.m. Thursday as he was putting a folder in the backpack at the end of the day at an after-school program at Universal Samuel Daroff Charter School.

The principal said staff members immediately took the backpack and called police.

Lt. John Walker said police were interviewing the boy’s family and reviewing surveillance video to figure out how the gun got into the bag.

Walker says it was a .38-caliber handgun loaded with five rounds of ammunition.

The boy said he had his backpack with him in the classroom the entire day.