Police say they were made aware of the incident at 11:45pm on July 12, when they received reports an ATV had rolled on private property in the town's south west.

St John Ambulance and police then attended the Cossack property, where a 47-year-old man was declared deceased at the scene.

Police say a second man, in his 30s, was taken to Katherine Hospital with non-life-threatening injuries.

Detective Senior Sergeant Paul Lawson said police would continue to investigate the circumstances surrounding the incident.

"A crime scene has been declared as police investigate the circumstances of the incident," he said.