A four-year-old shot a single round, killing the wife of a Tennessee sheriff’s deputy at a family gathering.

Wilson County Deputy Daniel Fanning was showing his guns to a relative in his bedroom at his Lebanon home on Saturday. No one saw the young child enter the room, grab a weapon and discharge one round.

Sheriff Robert Bryan told the Associated Press the bullet hit 48-year-old Josephine Fanning. Her Irish American husband desperately performed CPR in repeated failed attempts to revive his wife whom he had married last year. She was pronounced dead at the scene.

The small boy, a guest at the cookout, was not related to the couple.

Bryan said “Split second, we're talking about seconds for that kid to walk in that room unbeknownst to them, grab that gun and it goes off.”

He explained that Fanning wanted to show his relative another rifle he had in his bedroom. Fanning went to the locked gun cabinet and had to remove the handgun to retrieve the rifle. He placed the handgun on the bed for just a moment. No one saw the small child enter the room.

The Sheriff told the local news station, “He took all the precautions, he's a trained law enforcement officer, trains with weapons all the time.”

The gun was Daniel Fanning's personal weapon and he was not on duty at the time. He is a school resource officer at Sam Houston Elementary School and the school officials said that the family was in their prayers.

The Tennessee Bureau of Investigation is investigating the incident.

Gun-friendly Tennessee has one of the highest rates of fatal accidental shootings in the nation, according to federal health statistics.

Here’s the 5KSDK report: