A fire broke out at the Forest Products Distributors building around 4:30 a.m. Thursday.
According to Rapid City Fire Department Lt. Jim Bussell, the fire started in a dryer used to dry pellets used for wood-burning stoves. It spread to sawdust around the initial fire.
Firefighters have an extension to other areas nearby as well.
It will be an extensive overhaul operation due to the massive amounts of sawdust. Firefighters have stopped the forward progress of the fire.