“At this stage, the fire is being treated as unexplained and inquiries by emergency services will continue this morning to determine the full circumstances,” a spokesperson said.
Images of the blaze show thick plumes of smoke filling the air.
A Herald photographer said many police officers armed with Bushmasters were outside the address.
The house was “utterly destroyed”, with the roof partly collapsed, he said. Fire crews were working around the address with several houses.
Red Hills Rd was closed for several hours between Sunnyvale Rd and Puhikawa St.
The fire was extinguished around 10.30pm but one fire truck remained to dampen down the hotspots overnight, Fenz northern shift manager Carren Larking said.
Two fire investigators had attended the scene in the dark and could return this morning, she said.
Five appliances attended from West Harbour, Te Atatū, Waitākere, Henderson and Auckland City.
A New Zealand Defence Force spokesperson said an explosive ordnance disposal team responded to a request for assistance from New Zealand Police at the address, where an item was identified that appeared to be explosive in nature.
“The item was investigated and discovered to be hazardous and was subsequently disposed of by controlled demolition,” they said.
Another police operation was carried out at a property on the same street in 2023, where officers were seeking a wanted person.