Central Huron Fire Chief Dave Renner says they're now in the process of opening up one lane along Highway 4 (Albert Street) in Clinton following an early morning fire.
Renner says the fire appears to have started upstairs inside an empty apartment, one of 5 apartments in the affected building.
Only two of the apartments are said to be occupied while 3 remain vacant.
The building has stores at either end of the block below the fire zone, the stores in between were unoccupied.
There is no cost estimate on damage at this time and no injuries were reported.
Investigators with the Ontario Fire Marshal's Office have been called in to investigate.
With files from CKNX Correspondent Bob Mongomery