The feds are in Windsor to figure out the cause of the fire that destroyed that town's best known historic landmark.

The Bureau of Alcohol, Tobacco, Firearms and Explosives sent a special investigation team - about 20 people - who start their on-site work Tuesday morning.

The Windsor Mill fire began early Sunday morning. Not much is left of the structure that dated to the late 1800s.

“This will go down as one of the largest fires in this town’s history,” Windsor-Severance Fire Rescue spokesperson Todd Vess said. “[The mill] went up like a matchstick.”

The grain mill was Windsor- an iconic symbol built in 1899 to store the town’s food supply. Over the years it acted as a pillar in the small Weld County town until the 1990s when it was decommissioned. In 2008 the mill was damaged by an EF-3 tornado that ripped through the town, one of Colorado’s worst tornadoes in history.

Developers were turning it into a new brewery and restaurant. Eight months of work had gone into the project until Sunday’s fire.

The fire department in Windsor is still dealing with hot spots.

There were no injuries in the fire, but firefighters are still looking into a cause.