UPDATED REPORT - Two people are dead after a French jet trainer crashed into the sea in the Firth of Thames at Kaiaua, east of Pukekohe, this morning.
The plane is understood to have flown out of Ardmore, south of Auckland and crashed about 10am.
It is understood to be just 100 metres offshore. It is low tide about 1pm.
St John ambulance confirmed two died in the crash.
Kathryn Caulfield, of St John Ambulance, told NZPA at 11.45am that one body had been recovered and the other was still in the plane wreckage.
An eye witness who saw the jet crash told National Radio it had been doing aerobatics before plunging into the rocky water.
"It went up into the clouds, did a couple of rolls and a couple of loops and sort of came down spiralling and went straight in," he said.
Westpac Rescue Helicopter Auckland chief executive officer Rea Wikaira told NZPA the jet's wreckage was spread over a wide area.
"From that, we know it would have been a high velocity impact," he said.
A staff member at Kaiaua fish and chip shop, who did not want to be named, told NZPA that customers outside heard "a big boom" around 10am.
"The plane really made a big noise when it crashed into the water," she said.
"There are a lot of people with boats here and some went out to see what they could do. There were helicopters flying overhead and emergency services arriving."
The New Zealand Warbirds Association said the aircraft was a 1960 Fouga CM170 Magister.
Built by a Toulouse-based company, the first production Magister flew in 1955 and more than 900 of the aircraft had been constructed when production stopped in the early 1970s.
Designed as a trainer, the Magister was used by many countries as a light attack aircraft. Israel employed it in combat in the 1967 Six Day War.
The Warbirds' website said there was only one example of the Magister in New Zealand.
That plane first entered service with the French air force in June 1960 and was rebuilt in 1983 as a light strike aircraft.
It was retired in 1995 with a total of 2380 hours of flying time logged.
It was imported to New Zealand disassembled in early 1998 by the late Dougal Dallison.
The aircraft was reassembled and registered as ZK-FGA in March 1998.
On Mr Dallison's death, the aircraft was sold to a Warbirds syndicate and based at Ardmore.
The Fouga has a wingspan of 12.15m and a length of 10.06m. It can reach a maximum speed of 725km/h at 9000m and has a range of 1400km.