Three men are injured, one seriously, after a yacht came off its moorings and ran aground during a storm on Sunday night.

The boat ran aground on South Island, just south of Rakino Island in Auckland's Hauraki Gulf.

An Auckland Westpac Rescue Helicopter spokesperson says a chopper crew was alerted about 9.10pm.

After locating the yacht, they winched three men off in what was described as 'challenging conditions”.

They were flown to Auckland City Hospital.

One was in a serious condition, while two were in a minor condition.

The spokesperson says it's believed the rescue was delayed for a short time due to the weather.

'It was quite tricky conditions last night.”

The rescue took place about the same time as a tornado hit east Auckland, downing trees, ripping out fences and lifting roofs.

One resident described glass flying through his home 'like bullets” after a window blew out.

South Island is about 20km from Auckland's Half Moon Bay.

A spokesperson from Maritime New Zealand's Rescue Coordination Centre says those on board set off an EPIRB (emergency position-indicating radio beacon), as well as making mayday broadcasts.

'The skipper informed [the Rescue Coordination Centre] there were three people on-board, and the vessel was sinking after it hit rocks. Everyone on board made it to South Island.”

Coastguard was unable to extricate them from the island and the Westpac chopper crew carried out the rescue, the spokesperson said.

'This was a complex rescue in tough conditions.”

-Stuff.