Two people have been rescued after a small helicopter crashed and sank into the sea off Auckland.
The KC 518 Composite Helicopter was seen to go down into the seas in the channel between North Head and Mechanics Bay.
The pilot of the crashed helicopter, Peter Maloney, has told reporters engine failure was the cause of the crash.
He saw a warning light and then heard an audible warning which told him "I was losing power''.
He said the helicopter was a prototype of his company Composite Helicopters.
Auckland Westpac rescue helicopter pilot Barry Watkin saw the splash as the chopper hit the water.
"There was an almighty splash as the rotor blades hit the water."
A second chopper was accompanying the one that crashed which hovered over the location, he said.
The pilot was able to make a mayday call and performed a "semi-controlled " crash where the chopper turned on its side, which killed the rotor blades and allowed him and a passenger to escape uninjured.
It was submerged under a metre of water.
A navy boat in the area was first on the scene and was quickly joined by police boats
Mr Watkin said it was an extremely unlucky thing to happen - but those on board were also incredibly lucky to walk away uninjured.
"I'd be going straight to the lotto shop," he said.
A Navy spokeswoman said the inshore patrol vessel HMNZS Taupo happened to be sailing from Devonport Naval Base at the time of the incident.
"It was very much in the right place at the right time to provide rapid response to that emergency."
The spokeswoman said it was not a Navy helicopter, and she could not immediately confirm whether the two injured people were taken to Devonport Naval Hospital.
Navy personnel used inflatable boats to get to the site.
There was no sign of the helicopter on the surface of the water.
Fire Service spokeswoman Megan Ruru said their services were also responding to the crash.
"We've been advised that there is a helicopter into the water which is just off North Head. Two persons have been rescued and we're currently liaising with Westpac and the police."
The Westpac Rescue Helicopter was asked to assist, but isn't involved in the rescue.
The Fire Service is also responding to the crash.
The downed machine is from Composite Helicopters - a firm based on the North Shore, at the Dairy Flat airfield.
The KC518 is a lightweight carbon and Kevlar craft and described by the firm as the world's first all composite frameless helicopter airframe.
They are sold as kits.
