No one was injured, said Greeneville Police Capt. Steve Hixson.
The robber is described by police as a white male in his late 20s or early 30s, about 6-feet-tall and of medium build, weighing about 200 pounds.
He was wearing a waist-length camouflage hunting coat with a large hood he wore during the robbery, and baggy-style jeans, Hixson said.
Anyone with information about the suspect or the robbery can contact the Greeneville Police Department at (423) 639-7111. Detective Robert Vereecke is lead investigator on the case.