Mr Simpson said they expected to be at the scene much of the day.
"Police and fire safety have an investigation under way and at this stage a cause has not been established.''
A fire appliance from Gisborne responded but was turned back and a tanker was later sent to assist with the dampening down operation.
Detective Sergeant Theo Akroyd said it was too early yet to determine if the fire was suspicious.
"We will work closely with the fire safety investigation officers to determine the cause of the fire. But at this stage we can't say whether the fire was accidentally or deliberately lit.''
A post-mortem examination will be conducted to determine the identity of the person found inside.
Police say an elderly man lived in the house and was well known in the Whatatutu-Te Karaka area.
