Post-mortems will be done today on the bodies of a woman and a man who were fatally stabbed at a property in The Drive, in the Auckland suburb of Epsom yesterday.
Two other people were taken to hospital - one in a critical condition and one with minor injuries.
The house is under guard but the police say those who died were known to each other and there is no risk to the community.
Detective Inspector Scott Beard said the people involved have not yet been formally identified.
Part of the police investigation will be providing victim support to the family members involved, he said.