FULTON COUNTY, Ga. -- Officials said two students were injured inside a Fulton County high school classroom after a gun accidentally fired.

According to Fulton County School District spokesperson Susan Hale, school police received reports of a "loud pop" coming from a 9th grade Banneker High School classroom around 3:30 Thursday afternoon.

School officials said an assistant administrator went to the classroom and noticed a "small spattering of blood" on the floor. He immediately called 911 and the classroom was placed on lockdown.

When officers got to the room, they found one student shot in her ankle. Another student was grazed by the same bullet, police said. They're both being treated for their injuries, which officials said were minor.

Initially, school staff thought that a circuit had broken or the school had experienced a mechanical malfunction. After searching the classroom, however, officers found a low-caliber handgun hidden in a box inside a student's backpack.

School officials believe the student brought the gun, which may have been a family heirloom, in a box that he brought in a backpack.

Two other students, who reportedly knew about the gun, began jostling the backpack and the gun accidently fired, officials said.

The student who brought the gun onto campus will face a weapons charge. The other students will face reckless conduct charge.

Anthony Pinchem, 18, is a football player at Banneker and was surprised when he heard that fellow students were shot.

"You never think it’ll happen in school. It’s crazy," he said. "It makes me watch who I’m around. I watch my surroundings more at school. It’s a lot."

Hale said Fulton County schools don't have walk-through metal detectors, but security guards do have wands.

While the initial investigation indicates the gun fired accidentally, Fulton County School Police said they do plan to file criminal charges "against everyone involved in the incident according to district policy."

According to Georgia Department of Education disciplinary data for the last school year (2015 to 2016), this is not the first time a a gun has been found on Banneker school grounds. In that time period, 17 guns were found inside Fulton County schools, two of those (including this incident) at Banneker High School.

A total of 124 guns were brought on school grounds across Georgia last school year, though the top five school districts where guns were found are all in metro Atlanta. Fulton and APS topped the list with 17 guns found. DeKalb was next with 12 guns. Cobb and Gwinnett rounded out the top five with seven and six guns, respectively.

This school year (2016 to 2017), Fulton leads the pack with guns found on campus -- 22 this year so far. DeKalb is in second with 18 guns, APS follows with 16. Chatham and Cobb are fourth and fifth with six and five respectively.

In a letter to parents, Banneker's principal Dr. Duke Bradley explained what happened, promising parents additional details as they develop. Additionally, Bradley said no bags of any kind would be allowed inside the building.

"Any bags brought in will be confiscated," the letter reads. "Rest assured that the safety of every person within our school community is our primary concern, and we would appreciated your support in these efforts."