PITTSFIELD — Four families escaped into sub-freezing weather early Sunday morning as fire raced through their apartments, gutting the mixed-use building near the William Stanley Business Park.

Members of one family were taken to Berkshire Medical Center to be treated for apparent smoke inhalation, officials said. It was not clear how many were injured or how seriously.

An unknown number of residents had safely fled the second and third floors at 10 Dalton Ave. when firefighters arrived around shortly after 3:35 a.m. to find the three-story, wood-frame structure heavily engulfed in flames, according to city fire officials.

"The balloon-frame construction contributed to the fire spreading so quickly," said Pittsfield Fire Chief Robert Czerwinski.

The chief noted the flames shot through the roof, which eventually collapsed onto the upper floor apartments.

Based on a preliminary investigation, Czerwinski believes the fire began in the first floor office of Cavalier Management, which owns the building near the intersection of Tyler Street and Woodlawn Avenue. As of Sunday afternoon, investigators from city and the State Fire Marshal's Office were still sifting through the rubble to find out what ignited the fire.

With the help of ladder trucks from Williamstown, Adams and Lenox fire departments, all available Pittsfield firefighters had the blaze under control by 6 a.m. Pittsfield has been without either of its aerial fire trucks for a couple of months.

A third ladder truck was summoned due to the icy temperatures.

"It was 24 degrees when I left my house," Czerwinski said. "At one point the ladder on the Lenox truck couldn't retract so we called in another."

The fire briefly left the residents out in the cold, but Cavalier Management was finding temporary shelter for their tenants in other apartments they own/manage in the Pittsfield area, according to city fire officials. The American Red Cross disaster relief specialists were called in to help the victims get back on their feet.

After fire investigators finished sifting through the rubble, the city will demolish 10 Dalton Ave., leaving intact the rest of the building at 6 and 8 Dalton Ave.

Dalton and Lanesborough fire departments backed up the city firefighters by covering the the Columbus Avenue headquarters. The fire

forced Pittsfield police to detour some traffic around the fire scene well into the afternoon.

Reach staff writer Dick Lindsay at (413) 496-6233.