They found the home ablaze and summoned fire crews from surrounding areas to put out the flames.
Once they were able to enter the home, authorities found six victims from the same family dead inside.
A seventh person who was shot three times survived and is being treated in hospital, in what authorities are describing as a “domestic incident”.
Marion County Sheriff Bo Burnett identified the suspect as Gary Barnett, who died at the scene. His estranged wife Regina Barnett, and her daughter Britney Perez, are also among the deceased.
Two of the estranged couple’s grandchildren, and a third child are also among the victims.
The names and ages of the three children have not yet been released. Two of the victims died from smoke inhalation, authorities said.
Sheriff Burnett told WSB-TV the scene was “one of the worst I've been involved in all my career as a law enforcement officer”.
Court records obtained by WSB-TV show Regina Barnett had taken out a protection order in 2022 after her husband was charged with domestic assault.
According to the documents, Regina Barnett told a judge that her soon-to-be ex -husband had threatened to shoot her and her dog, and verbally abused her “every day”.
“He also has anywhere from 50 to 60 guns in his room. I am afraid he will get drunk and shoot me,” she told the judge.
The protection order was still in effect, Sheriff Burnett told the news station.
“It’s a domestic situation, evidently that has been ongoing for a pretty good while,” he said.
Neighbour Sylvia Cooper told WTVC she heard breaking glass and five gunshots.
The Tennessee Bureau of Investigation is assisting with the investigation.