At least three people are dead after a boat sank overnight off the North Cape with 10 people on board, police have confirmed.

Five people were rescued from the water but there are two still missing after their boat - understood to be the fishing charter Enchanter - got into trouble and set off a distress beacon around 8pm.

Police said the bodies of two people had sadly been found in the water and were recovered by helicopter this morning.

A third body had been recovered by a vessel assisting with the water search.

"Air, land and water searches are ongoing in efforts to locate the two people who remain missing," police said.

An emergency beacon alert was received last night around 8pm from southeast of North Cape, according to Maritime NZ spokesman Nick Burt.

Maritime NZ runs the Rescue Coordination Centre which is in charge of the rescue effort.

A helicopter was first on scene at the remote location, arriving around 11.40pm, Burt said. Multiple agencies were involved in the rescue including police, Westpac rescue helicopters, local fishing vessels and the NZ Defence Force.

Ground crews, including police, are also searching along the shoreline.

Five people were rescued from the water and were in Kaitaia Hospital in a stable condition, Burt told NZME. He was not sure if the boat's skipper was among them but said police had been interviewing the survivors.

The weather had been "pretty atrocious" overnight, he said. "It has abated now - we're seeing quite favourable conditions - but it has been a quite dangerous rescue for the crews."

Northland has been battered by severe weather overnight including torrential rain and thunderstorms.

MetService was warning of gales and possible thunderstorms off the coast overnight.

Burt said the operation was highly technical, with a number of agencies working together to look for the remaining five people.

"The operation has been challenging due to the weather conditions and poor visibility."

NZ Defence Force spokesman Dave Williams said a P-3K2 Orion had left the air force base at Whenuapai at 1am to help with the search.

That aircraft, with a 12-person search and rescue crew, had returned and was due to land at Whenuapai Base Auckland around 8am but had been diverted to Base Ohakea due to poor weather.

A second Orion had been requested and would be leaving Auckland as soon as possible, Williams said.

The Royal New Zealand Navy ship HMNZS Taupo was also en route to the search area and was expected to arrive around midday.

Williams said it was also possible one of the defence force's Seasprite helicopters could join the search. It was currently on board HMNZS Canterbury which is in the Hauraki Gulf.

Auckland's Westpac Rescue Helicopter that it had responded last night to a search and rescue call for a sunken vessel 200 metres off the coast of North Cape.