Fires that destroyed two vacant mills in Connecticut are under investigation.

The Norwich Bulletin reports more than 140 firefighters from dozens of area departments battled the fierce flames Saturday at a 120-year-old former cotton mill in Killingly and at a former factory building about 26 miles away in Windham.

No injuries were reported in either blaze and the state fire marshal’s office is investigating to determine the causes.

Residents of Killingly were urged to stay indoors as a precaution. An official said state and federal environmental officials were monitoring air and water quality around the mill to make sure no hazardous chemicals were released during the fire.

Records show the property had been sold to in August 2018 to Hartford-based Shennecock Realty through a foreclosure process. The Windham mill had been sold to Wing Hing LLC in 2013, property records state, and while the Bulletin reports it was in the process of being redeveloped, it was vacant at the time of the fire.