Mr Dever said there were immediate concerns for the safety of the couple who were known to be living in the home. "They were house-sitting for their son."
It's understood the couple were aged in their late 70s or early 80s.
A fire crew from Gisborne went to the scene to relieve the Tolaga Bay volunteers.
Once the damping-down process had been completed, police and firefighters began to sift through the remains of the house in a search for the couple.
"It has been a difficult process," said assistant area fire commander Peter Clark.
Extensive inquiries were made in the Tolaga Bay area to determine whether one of the elderly couple might have been away at the time.
"Tragically, we felt pretty sure that the bodies of both elderly people would be found in the remains of the house," Mr Clark said.
The house was all but destroyed in the blaze. "The roof is on the ground and only parts of two walls are still standing," Mr Clark said.
Detectives from Gisborne have started an inquiry into the fire.
"The cause is unknown at this stage and is being investigated in conjunction with specialist fire investigators," said Detective Senior Sergeant Craig Scott.
Neighbour Gwen Gordon said she had seen the couple's vehicles at the house and thought they were inside the property.
"They were house-sitting for their son, who lived in Australia, and had only been at the property for three months. They were just lovely. It's terrible."
Uawa Parade resident Delys Hooper said the house was old but recently renovated.
"It's just horrible. I woke up when I heard all the sirens and went out the front of my house and couldn't see anything except the smoke.
"Then I went outside and just saw all the flames. The fire was huge."
