Firefighters battled a fire in a duplex in Chelmsford, Massachusetts, on Friday morning.
The fire broke out shortly after 6 a.m. on Quigley Avenue.
The back side of the house wound up collapsing. Residents of the building were saved by a neighbor who saw the fire and began knocking on windows to get everybody out safely.
"Anyone would have done the same thing," the man told NBC10 Boston.
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Aerial footage showed heavy flames and smoke coming from the building, with multiple police and fire vehicles surrounding it.
No details on the fire were immediately available from fire officials.