There was only one person in the house at the time.
Police were already on the scene when fire crews arrived because there had been reports of an explosion, Mr Duley said.
"I don't think it is thought to be suspicious."
The house was fully destroyed but no other properties were in danger as the nearest house was about 50m away, Mr Duley said.
"There was nothing [left] standing, it was a ferocious fire.
"We seemed to think it might have been going for a while."
Wairoa sent three appliances and a tanker and the Nuhaka brigade also brought an appliance and a tanker.
Fire crews were at the scene until about 4.30am and only finished putting the blaze out about 4am.
They were called back about 6.30pm on Saturday because an outlying shed which had been smouldering on the property had reignited, but it only took 10 minutes to put out.
Senior Sergeant Mike Stevenson said a Gisborne Criminal Investigation Branch detective attended on Friday night and a CIB team conducted a scene examination on Saturday, as well as a fire investigator.
"They were trying to establish how the fire started."
The scene was guarded overnight on Friday before the examination on Saturday morning.
He expected the name of the deceased would be released sometime this week after a formal identification had been made and next of kin had been advised.
Two Kiwi Rd residents said they did not hear anything as they lived on the other end of the road to the house.
One said they even slept through all the noise and did not hear about the fire until the morning.
A St John spokesperson said an ambulance was called to the fire about 10.45pm but no further information could be provided due to the incident being fatal.
