The gunman, believed to be a day-shift employee, shot three people at the facility in the Nashville neighborhood of Antioch just before 6 a.m. during a change of shifts, Metropolitan Nashville Police Department spokesman Don Aaron said.
Police officers encountered the gunman shortly after the shooting, and the gunman directed a semiautomatic pistol at them after being told to drop his weapon, Aaron said. Police then shot the gunman, Aaron said.
The gunman had shot one employee in the chest; one in the abdomen; and one in a leg, Aaron said. One of the three was in critical condition Tuesday morning, he said.
Earlier, police said the gunman had shot two people.
A fourth worker injured her ankle while running, Aaron said.
No names were immediately released. Police also have not commented about a motive.
The gunman had been working there “for a relatively short period of time,” Aaron said.
SmileDirectClub is known primarily for working with dentists and orthodontists to sell clear aligners online as an alternative to traditional braces.
The Antioch neighborhood is about a 12-mile drive southeast of downtown Nashville.