Residents of Wickham are advised to keep their doors and windows closed as Fire and Rescue NSW crews battle a large fire in an auto-electrical business.
The blaze broke out in the Foundry Street premises just after 3.30am.
Twelve fire trucks, including an aerial platform, and around 40 firefighters rushed to the scene where the flames consumed dozens of cars and engulfed a building.
The roof of that 200m x 200m building has collapsed and a cloud of thick, black smoke enveloped the area.
FRNSW is urging Wickham residents to keep their doors, windows and vents closed to prevent infiltration by the hazardous smoke.
The blaze has been contained, preventing the spread of flames to neighbouring properties in the industrial area.
Once extinguished, firefighters will begin investigations into the cause and origin of the fire.