It happened just after 4 a.m. at a vacant structure in the Freedom Industrial Park.
Large flames were seen coming from the building when crews arrived.
Multiple fire departments responded including Hermon, Bangor, Levant, Newburgh, Carmel and Glenburn.
No one was injured.
Crews were able to contain the fire to the back end of the structure.
"We put interior crews in early," says Mike Simmons of the Hermon Fire Department. "We were able to hold it from extending into the front of the building just on that fire wall."
"It was a slow responding for all units due to the weather this morning," he added. "That definitely delayed responses of all mutual aid companies to getting out here."
They are working to put out remaining hot spots.
Firefighters are not sure of the extent of the damage to the building or where the fire started.