Investigators are working around the clock to determine what sparked a huge fire that destroyed a building and damaged planes at Danbury Airport Wednesday.

Investigators say they don't believe the fire was suspicious, but they are continuing to investigate. They spent Thursday sifting through the rubble, hoping to find some answers.

The fire broke out around 10 p.m. at the Reliant Air hangar on Wibling Road. Early damage estimates are between $20 million and $25 million. Investigators believe the building is a total loss. More than a dozen fire engines from Danbury, Ridgefield and Bethel battled the blaze. However, it proved difficult to extinguish because of the jet fuel in the hangar. Airport administrators say 11 planes and a restaurant were damaged. An estimated 20 people are now out of work. No one was hurt in the fire. Investigators are looking into issues with asbestos on the scene and runoff of jet fuel into a storm drain.