Two women who have been found dead at a home in the Auckland suburb of Ranui are thought to be mother and daughter.
Detective Inspector Greg Cramer said it appeared the pair had been stabbed this morning but a post-mortem examination would be held in the next few days.
A male occupant from the house was helping with inquiries and police were not seeking anyone else over the deaths.
Police said the 55-year-old man, who was known to the victims, made a 111 call to police, and was at the scene when police arrived.
Formal identification was expected to take 24 hours.
The scene examination would take several days, police said.
Police were also speaking to other members of the family.
"Police were called to the address about 10 o'clock this morning. Upon staff arriving we found the bodies of two women inside," Mr Cramer said.
The women were related but he did not say how. One was in her 50s and the other in her 20s.
"We believe that there is a family relationship but until such time as formal identification has taken place we can't say," said Mr Cramer.
The bodies remained inside the house this afternoon and police had erected a large blue and white tent in an adjacent yard and removed a section of fence.
The road was open to one lane only.
Neighbour Rib Nixon lives in the adjacent house on Pooks Rd and said he believed a middle-aged couple with an adult daughter lived at the address and were often visited by some adult sons.
The arrival of police at about 10am today was the first sign that anything was amiss, he said.
"I didn't hear anything. My wife got up and went to work like every Monday and then I heard something going on outside and it was the police."
He saw three ambulances arrive and paramedics speaking to the male resident, before he left with police.
"They were always very friendly.
"I used to talk to them and say hello - that sort of thing."
Police had also enquired with Mr Nixon but were unable to tell him any information about what happened.
They did not believe he was in any danger, he said.
The family had lived in the house for at least three years, he said.