Morgan Tukes was arrested after being treated at the hospital for a gunshot wound to the leg.
Tukes' mother, Kimberly Johnson, said that her daughter didn't know she was carrying a gun in her pocket.
"She said she didn't know it was in there in her pocket because she just grabbed her jacket and didn't know that it was in there," Johnson said.
The mother said that her family doesn't have any guns in the house and she doesn't know where she got it from.
"We don't own guns, period," said Johnson.
Tukes' parents say the senior is just two months from graduation.
"I just hate for this to mess up her opportunity for her to go to college because I was trying to send her to college. She just received her SATs the day before yesterday. She did good on the SATs so we were kind of excited," said Johnson.
Her mother says she believes her daughter made a mistake.
"Some people learn them young, some people learn them old. I feel like this is a lesson learned for her. I feel like everything that you go through is a lesson learned. It happened for a reason. God let it happen for a reason," Johnson said.
Students described Tukes as a student athlete who is sweet and popular.
"She knows everybody. She's cool with everybody," said one classmate.
Tukes was being held at Fulton County Jail Wednesday night on charges of carrying weapons within a school safety zone, reckless conduct, possession of a pistol by a minor and disruption of a public school. She is scheduled to make her first court appearance on Thursday morning.