"All the lights were going so I came out to have a look.
"I could smell the burnt smell."
Fire crews left the property about 6.30am.
Housing NZ area manager Teresa Pou said its thoughts were with the family.
"The cause of the fire is still being investigated by the New Zealand Fire Service so we cannot speculate or comment on the possible cause.
"The health and safety of our tenants is our main priority. The smoke alarms in the property all worked and alerted the family to the fire."
She said staff quickly provided support to the tenants and contacted them to discuss what support they needed.
"They will be temporarily put up in a motel at our expense while we work on getting them a new home.
"Helping our tenants and their families stay safe is a big part of what we do as the country's largest landlord."
Over the past few years Housing New Zealand had rolled out several programmes to protect tenants outside and inside their homes, she said.
"This includes our smoke alarm upgrade which includes the latest photo-electric technologies that are employed to provide early warnings in case of fires inside houses."