Fire investigators believe they know what caused that huge fire in Gallatin this week. Officials say the natural gas components failed in a suspended heating unit, sparking the fire.

The blaze destroyed two businesses and damaged two adjacent buildings on the town square in Gallatin Wednesday afternoon.

Investigators have pegged the damage at $300,000.

Fourteen Gallatin firefighters were joined by 75 others from 13 agencies in the surrounding area. A total of 16 fire engines, a rescue unit and three ladder trucks responded.

There were no serious injuries.