A manhunt is underway for the suspect in a mass shooting at the Waffle House on Murfreesboro Pike in Antioch, said police.
He then walked into the restaurant and continued his shooting rampage, he added.
"The shots had stopped so he made a decision to rush the gunman, actually wrestled that assault rifle away, tossed it over the counter and, at that point, the gunman fled", police spokesperson Don Aaron said.
"He did not say anything", said Chuck Cordero, 50, who was at the Waffle House. One person later died at a hospital where two others are being treated for injuries.
Police said they were looking for 29-year-old Travis Reinking of Morton, Illinois, as a person of interest in the shooting.
Police believe Reinking's father claimed the weapons after they were confiscated and returned them to his son. Police department spokesman Don Aaron says Shaw's actions were similar those of Robert Engle during the Antioch church shooting previous year.
Police say the gunman was naked and using an assault style weapon.
Authorities suspect that the gunman, who is still on the loose, may have two weapons on him: a long gun and a handgun.
The man who wrestled the rifle away from the shooter inside the Antioch, Tenn.
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Also killed outside was 20-year-old Joe R. Perez, of Nashville, who was a patron of the restaurant.
"I hope we can bring violence in all facets - not just gun violence, but all facets of violence - to an end", he said.
When the shooting momentarily stopped, a Waffle House customer took advantage of the moment. The other is in critical but stable condition. Police say the suspect fled on foot, and is still on the loose.
Aaron said witnesses saw a man in a nearby wooded area, and police were still tracking the man more than eight hours after the shooting.
"But I know it's going to take time".
The Metropolitan Nashville Police Department wrote on Twitter that the shooting occurred in an area southeast of the city at 3:25 am (0825 GMT).
A US congressman is calling for restricting access to some assault weapons in the wake of a shooting at a restaurant in Tennessee on Sunday that left four people dead.
Aaron said Reinking's firearms authorisation was then revoked at the request of the Federal Bureau of Investigation, and four weapons were seized, including the AR15 that he allegedly used in the shooting on Sunday.
He was taken to a local hospital by personal vehicle before officers arrived on scene, Thompson said.