Dalton Police said a social studies teacher at Dalton High School late Wednesday morning ordered students out of his classroom, then locked himself in.
Police said Jesse Randal Davidson, 53, had a gun and at least one shot was fired.
He was eventually taken into custody and charged with aggravated assault, carrying a weapon on school grounds, terroristic threats, reckless conduct, possession of a firearm during the commission of a crime, and disrupting a public school.
Police said Davidson apparently brought the gun onto campus in his computer case when he arrived Wednesday morning.
The weapon was a snub-nosed .38 revolver.
When the principal tried to get into room 413, Davidson refused to open the door. When the principal put the key into the door lock, Davidson fired the shot.
Spokesman Bruce Frazier said, "At this time, we don’t have any sort of a motive to release for his actions. He did not disclose his motivations to our investigator." Police said the shot went through a window.
Police said they do not believe there was any intent to hurt anyone.
Davidson, who has been at the school since 2004, is the play by play announcer for Dalton High football.
Authorities stressed that no children were injured, except for a student who injured an ankle while running in a hallway during the evacuation.
The area inside the school was evacuated and the school was locked down.
Parents were told not to go to the school, but to pick up their children at the Northwest Georgia Trade Center. Students waited in the gym to be bused to the center on Dug Gap Road.
School will be close at Dalton High on Thursday, but students will return on Friday.
The Georgia State Patrol also responded.