A person has died after they were injured during the Coastal Classic yacht race in the Bay of Islands.

The incident happened about 5km south of Cape Brett about 11.30pm on Friday, say police.

Coastguard Bay of Islands volunteers happened to be training nearby and responded to the distress call, says crew member Ayden Armitage.

“A crew member on board the yacht had been struck by the boom, rendering them unconscious and necessitating immediate medical attention.”

Coastguard, on board vessel Kōkako Rescue, reached and boarded the yacht with a medical kit and defibrillator about 1am.

“Sadly, the individual passed away.”

Two other sailors on the yacht were moderately injured.

The Coastal Classic passes by Rangitoto. Photo: Chris Weissenborn/Supplied.

The death has been referred to the coroner. (File photo)

"Our thoughts are with the whānau of the sailor and their fellow crew members who were on board at the time,” says Ayden.

The Coastal Classic is an annual 119 nautical mile race from Devonport in Auckland to Russell in the Bay of Islands, hosted by the New Zealand Multihull Yacht Club.

“Described as a drag race, it can be a sprint for the fastest boats who can finish in less than six hours, or a challenging marathon for the crew on boats that take more than 24 hours to reach Russell,” the event website reads.

Club Commodore Adrian Percival says it had been advised of the “serious incident”.

"Our thoughts are with the family, friends and crew.”

“We now turn to supporting our family of sailors.”

The club is working with Coastguard and Yachting NZ to understand the facts of the incident.

Coastguard accompanied the yacht back to Opua, where it arrived about 4am on Saturday.

It had been a strategic decision for the Coastguard crew to conduct night-time training to coincide with the Coastal Classic, which significantly reduced their response time.

The matter has been referred to the coroner, say police.

Caroline Williams/Stuff.