Dalton Police said a frightening incident at Dalton High School on Wednesday began when teacher Randal Davidson refused to come out of his locked classroom.
A detective said he was notified by staff at the school that there was an issue with Davidson. A female staff member said she could not get him to answer the door.
Principal Steve Bartoo then said he had heard a gunshot from Davidson's classroom. He said that prompted him to tell the front desk to put the school on lockdown.
Police officers took up positions outside the closed door, while a detective contacted him via a school telephone from an adjacent room. Davidson told him he was alone in the room. He said he had a .38 caliber pistol and had fired one shot through the window.
After speaking with Davidson for a few minutes, he agreed to place the gun on his desk and come out.
He was then taken to police headquarters and interviewed prior to being booked on several charges.
Dalton High was closed on Thursday, but will reopen on Friday.