JACKSONVILLE, Fla. -- A student at a Southside high school was arrested Wednesday after police said a gun was found in his backpack.

Sharron Jackson, 17, was taken into police custody at Wolfson High School.

According to police reports, the teen left his backpack in room with a teacher, and the teacher held the backpack and noticed something inside that felt like a gun. After reporting the find to an administrator, the gun was discovered.

Officials said the weapon was a loaded automatic handgun. Jackson, a senior at the school, was arrested.

Wolfson High School Principal Hammond Gracy sent a letter home to parents to let them know what happened.

He said the student likely left the backpack in a classroom and not in his locker because the school was performing random security checks Wednesday morning on students and the teen didn't want his backpack nearby if he was searched.

"I think that students know if we're doing systematic sweeps and going through backpacks and purses and coming into rooms and making sure the kids are safe. I don't think he wanted to have the backpack on him," Gracy said.

He said the searches are common at the school, but added that he made sure they were conducted on Wednesday because of rumors that had been spreading about threats of violence in other schools around the district. Gracy cited a threatening text message that had been sent to students at First Coast High School and tensions running high over the recent vote by the school board to not rename Forrest High School, which is named after Nathan Bedford Forrest a Confederate general believed by some to have started the Ku Klux Klan.

Gracy said the searches were meant to put any safety concerns at ease.

"Kids are sometimes frightened. We wanted to make sure we were very visible in supporting our students," Gracy said.

The school district said the incident was a class-four infraction, and Jackson would be automatically suspended for 10 days.