An Ashburton fire watch house spokesman said a commercial building on Robinson Street had been totally involved in fire since about 6pm.
The building houses four businesses, including an upholstery business.
There were six fire engines still fighting to control the fire and carry out searches, but no-one is believed to be inside. One of the businesses had gas cylinders it used for welding, which were inside the building.
"There have been some explosions and our guys are in there with breathing apparatus to do a search.
"The damage is done, now we just put the flames out."
- The Dominion Post