Nearby residents say Thursday night's blast could be heard from blocks away.
Officials with Gerdau Ameristeel Mill say one worker is being treated at a regional burn center. The company says in a statement that five others workers have been treated and released from a local hospital.
The names of the victims have not been released. Officials with the Tennessee Occupational Safety and Health Administration say they are still investigating the cause of the explosion.
Gerdau Ameristeel says it is working with authorities to determine the cause and is committed to worker safety.
The company uses an electric arc furnace to turn scrap metal into steel.