Emergency services found wreckage last last night of a cargo plane which had crashed near Waikanae, north of Wellington.
Police confirmed they had found the wreckage on land north of Paraparaumu.
Senior Sergeant Peter Thurston said the aircraft was a Convair freight plane, with two or three crew aboard.
It is understood the plane, which was en route from Christchurch to Palmerston North, disappeared from the Ohakea radar about 9.30pm.
The Kapiti Mana police area controller, Inspector John Spence, said some debris had been found in the water, about half a mile out to sea, and other debris had washed up on beaches in the Waikanae area.
There was no word on survivors.
The plane is understood to belong to Christchurch-based Airfreight New Zealand, which operates five Convair freight planes.
Airfreight New Zealand manager Murray Johnson said he was gathering information, and news of the crash was "very distressing".
The company is a subsidiary of Palmerston North-based Fieldair Holdings.
Three people died when one of its Convairs crashed into the Manukau Harbour in 1989.
One report last night said that a plane was heard circling low before a bang and that it crashed into the sea off Pekapeka.
A rescue helicopter was dispatched from Wellington and the Coastguard called in.
Locals on the Kapiti Coast alerted emergency services after hearing a bang and smelling aviation fuel.
The owner of the Sand Castle Motel in Pekapeka, Mabs Le Page, said the bang was loud, like thunder.
However, she saw no sign of flames when she looked outside. The noise sounded as though it was heading out to sea.
The plane crash occurred during very bad weather, which caused chaos in the area and is predicted to bring a polar blast to the upper North Island today.
Wellington was cut off by slips and flooding that closed State Highway 1 and the main trunk railway line between Plimmerton and Mackays Crossing and by the closure of State Highway 2, the Rimutaka Hill road to Wairarapa.
A flash flood also caused substantial damage in the coastal township of Paekakariki where 200 people were evacuated from their homes.
Police told motorists not to try to leave or enter Wellington as the Paekakariki Hill Rd was also blocked, meaning there were no detours available for State Highway 1.
In Auckland, ferry company Fullers cancelled two sailings to Waiheke last night because galeforce winds and a tide running against the boats would have made the 40-minute trip too rough.
But sailings were to go ahead once the tide turned because the boats are big enough to handle the conditions.
Vector had emergency crews on standby as the power lines firm prepared yet again for outages in exposed places. Winds up to 120km/h were forecast for Auckland's west coast and Waiheke.
The storm was expected to move away to the east of the country overnight but MetService weather ambassador Bob McDavitt said a sting in its tail would be a cold southerly outbreak expected to spread over both islands today.