Mahwah police officer Travis Canning was responding to complaints about a noisy birthday party on Victoria Lane around 2 a.m. Saturday.
He observed several vehicles in the the driveway and loud music coming from the home. Then, as he approached the back deck, he saw smoke emanating from inside. He opened the rear sliding door to alert residents and he was hit with a burst of heat and clouds of smoke.
He called the fire department before he went inside, where he found two men throwing cups of water at a small fire in a first-floor room where a washer and dryer were located.
Several party guests - who were in another part of the house - were ordered to evacuate, and everyone inside escaped safely.
The fire soon spread and eventually destroyed the home.
Police say it appears the party was a 25th birthday party for one of occupants. The homeowners were reportedly overseas, and their son was living in the house at the time.
Authorities say the fire appears to have started in the back of a washing machine that was not being used at the time.