Two bodies have been found at a house in Waipukurau in central Hawke's Bay.
Detective Inspector Rob Jones said police launched an investigation into the deaths of two occupants of a residential address.
The inquiry was launched after family members provided information to police shortly before 9am today.
Jones said police would be continuing their inquiries at the address over the weekend with forensic support from ESR.
"As the investigation is in its early stages it is too soon to speculate about what has occurred," he said.
"The names of the deceased cannot be released at this stage and information will be released to media when police are able to do so."
Four police cars and a security guard were the only obvious signs something was amiss at the quiet semi-rural property on the outskirts of Waipukurau this morning.
But there is police emergency tape over a gate down the private driveway and police officers speaking in quiet tones behind the lush hedging.
Despite the hot weekend weather, the road - a main thoroughfare to a popular beach - has minimal traffic, apart from the occasional local and a neighbour who looks anxiously at the vehicles parked on the roadside as she pulls from her driveway.
The area is populated by well-kept lifestyle blocks, many home to retired farmers.
Central Hawke's Bay Mayor Alex Walker expressed sympathy but said she could not provide any more information about what happened.
"My condolences go out to the family and friends of those people involved, and also to the Police and emergency services that are involved," she said.
She said she could not say more because "we have to respect the families and people involved in that situation".
The crash happened in Ōpārau near Ōtorohanga about 8.45pm on March 30.