Tenants in the complex on Monterey Place evacuated as the fire broke out at about 7:30 a.m., according to the Connecticut Post.
The temperature was about 10 degrees, and buses were sent in to keep the residents of the Norwalk Housing Authority building warm, according to dispatch reports.
Assistant Fire Chief Steve Shay told the Post that the fire that started on the first floor.
Three of the six apartments were declared unfit for occupancy, according to the Connecticut Post.
South Main Street, Woodward Avenue, and Grove Street were closed in the area while firefighters worked, police said.
Click here for the story at the Connecticut Post.
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