Fire investigators were also at the scene yesterday morning with the owners of the small house who live in Waipukurau.
It was being rented to a woman who had been living there with her two children although it was understood they had not been home at the time of the fire.
The couple who own the house said while the damage was not immediately evident from the outside, it was "pretty bad".
They got the phone call from the fire service about 4am.
"It's not what you want to hear," the man said.
"This was our retirement scheme."
He said while the property was insured they were in for a long seven or eight months until everything was put right again.
Police would not comment on whether there had been a possible break-in at the house.
"All we can say is it is under investigation."
The owners said the woman tenant was now staying with family.
