A fire broke out at Marcello's Deli and Catering in Danbury shortly before midnight on Monday night.
Dispatchers received multiple calls for smoke coming from a structure near Lake Avenue and Hobson Street. Dispatchers alerted firefighters who quickly arrived on scene.
When crews arrived, firefighters said they found a large volume of smoke coming from the roof of the business.
Fire officials said crews worked to put out a stubborn fire in the attic space of the business.
According to Danbury Fire Department, the fire eventually became a third alarm fire. Additional personnel and mutual aid from Bethel, Brookfield and Ridgefield Fire Departments, along with Danbury Police, Danbury Hospital EMS and Danbury Emergency Management responded to the scene.
Danbury Public Works also responded to the scene to assist with icy conditions.
Crews battled the fire in the frigid temperatures for a few hours before it was deemed under control, fire officials said.
There was nobody at the deli at the time of the fire and no injuries were reported.
The Danbury Fire Marshal's Office is investigating the cause of the fire.
A business next door to the deli told NBC Connecticut that the deli is closed on Tuesday.