Police got there seconds after the noontime blaze broke out and ushered two residents out of the 2½-story home on Winding Trail in the township's Fardale section, neighbors said.
Flames apparently ignited by a timer for the front door light went up the front wall and into the soffits and the house.
"It was going pretty good," but members of nearby Mahwah Fire Company 4 quickly knocked down the blaze, witnesses said.
The smoke eaters also safely got out two family cats, they said.
No injuries were reported.
Mahwah's fire companies and police were joined by mutual aid colleagues from Waldwick, Wyckoff, Hillburn and Suffern, as well as by township EMS.
An extensive overhaul was under way, particularly around the front of the home, where the majority of damage occurred.
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