Four people died in the fire on Saturday afternoon, including three children - aged 1, 5 and 7.
The bodies of two children were recovered on Sunday night and were blessed by the family with karakia.
The body of the adult was removed earlier. Manawatu Area Commander Inspector Ross Grantham confirmed it was the children's father.
Police have put up emergency tape roping off the entrance to the property. Down the driveway was a police car, and a police-branded truck was visible. A couple of flowers look to have been placed near the front of the driveway.
Police said their focus now would be on finding the third child's body.
"It's unimaginable, the tragedy for the families going through this," Grantham said. "We are working very carefully through the scene to establish how it started, and that's still going to take us some time."
He said it was too early to tell yet if the fire was deliberately started.
"It's pretty risky with the part of the structure still there and the dust that's generated from the fire, so it will take us some time just to go through and establish what's happened."
Grantham said police were not seeking information from the public at this stage, but if anyone knew anything, they could "reach out".
He said it was "unusual" for a house fire to begin in the afternoon.
By 6am, just under $95,000 had been raised for the children's mother through a Givealittle page. The page described the fire as a "devastating loss beyond measure" and their goal was to provide the family with the "space and security needed to grieve in solitude".
"In the midst of this unimaginable grief, she also lost her home and everything she owned. She is facing the hardest journey possible, stripped of her physical security, while navigating the deepest emotional pain."
Neighbour describes seeing the fire as it happened
A neighbour told RNZ he was working at his home on Saturday, when someone noticed smoke from the nearby property.
"We all came out to have a look and we saw a horrific amount of smoke coming from about 300m away, where the neighbour's house is - pretty thick black billowing smoke.
"It was a very, very windy day and we knew it wasn't any kind of controlled fire. We knew it was some sort of what we considered to be a house fire at that stage."
He said, over an hour, many firefighters turned up, attempting to put the blaze out.
An hour after it started, the blaze and billowing smoke was still visible. He believed it took two hours for firefighters to put the fire out.
"They were still dousing it down and there was just very slight wisps of smoke coming from the property two hours after it started."
He said State Highway 1 near the property did not open until 8pm Saturday.
The neighbour said that, during the fire, he was "pretty shocked" at what was happening before his eyes.
"Nothing we could do about it and just a feeling of kind of despair, I guess just watching what was going on.
"Knowing that a young family was potentially losing everything they owned and knowing that is going to be a very, very hard place to come back from.
"Just the thought of not knowing whether everybody was alright or not, and subsequent to that we found out, that isn't the case, which has made things 10 times worse."
Police are not looking for anyone else in relation to the fire.
