A former police officer in Bean Station was taken into custody shortly after the shooting and robbery at the Down Home Pharmacy, District Attorney Jimmy Dunn said.
Dunn said the former officer, Jason B. Holt, took “a large quantity of pills” during the late-morning robbery.
The Knoxville News Sentinel reported that the pharmacy owner and the customer died at the scene.
The two employees were flown by helicopter to the University of Tennessee Medical Center, where they were in stable condition, Dunn said.
Holt, 37, was apprehended by local police and sheriff’s officers, he said.
Tennessee Bureau of Investigation agents were summoned to the scene to assist, said spokeswoman Kristin Helm.
Authorities put up sheets to cover the windows of the pharmacy where the shootings took place.
“Bean Station is a very small town,” said resident Joyce Williams. “There’s been robberies here, but never shootouts.”
The town’s population is less than 3,000.
The Bean Station police chief did not immediately return calls to the Associated Press.