Fire fighters responded to the Tarco Steel building on Spud Lane around 11:00 am.
Manager Rick Simon tells Action News about 13 people were inside when the fire started.
Everyone made it out safely.
The Tarco building flooded in June and crews were inside replacing the insulation.
Broome Fire Investigators are looking into whether the insulation and steel dust combusted.
The building houses steel products.
The damage is structural.
Simon says Tarco will resume work on Thursday.