A female resident was hospitalized with smoke inhalation during the three-alarm blaze, which was called in around 4:15 a.m. and sent flames shooting up through the walls, severely damaging the Walnut Street home, Deputy Fire Chief Tom Loreto said.
Surrounding homes were evacuated as a precaution.
Mahwah firefighters were assisted by their colleagues from Ramsey, Wyckoff, Midland Park and Ho-Ho-Kus, among others. They had the blaze doused by 6 a.m. before hitting hot spots.
The Bergen County Sheriff's Bureau of Criminal Identification collected evidence so that county prosecutor's detectives could determine the cause and origin, authorities said.
Click here to follow Daily Voice Rutherford and receive free news updates.