A "household plumber" working in the Bogert Road house near Midland Avenue apparently ignited the blaze around 2:30 p.m., River Edge Deputy Fire Chief David Stucke told Daily Voice.
An upstairs bedroom was fully involved when emergency responders arrived, he said.
"I was on a conference call when I saw the smoke," next-door neighbor Colleen Morrell told Daily Voice. "I said, 'I gotta go'."
River Edge firefighters were joined by their colleagues from Oradell, New Milford and Parmus, as well as a Hackensack FAST.
River Edge and New Milford EMS also responded.
The blaze was brought under control within an hour and 20 minutes.
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