Bureau spokesman Josh DeVine says the shooting happened about 5 p.m. Wednesday in the town of Lobelville, about 75 miles southwest of Nashville. A longtime member of the National Guard was killed.
DeVine says the victim's name won't be released until his family members had been notified. He says a top official, Maj. Gen. Max Haston, identified him as a sergeant first-class who had been with the guard for 20 years.
Devines says the armory is usually locked and it was unclear how the shooter got into the building.
No charges have been filed.