"The yacht is now completely underwater with only the mast visible," Larsen said.
Auckland Rescue Helicopter chief crewman Mark Cannell said they responded to a request for assistance at about 5.20am.
"We were initially advised there were six people in the water, but were updated on route they were all on the rocks near the vessel."
Their helicopter picked up two children and two adults, while the other two were picked up by Northland Rescue Helicopter. All were taken to Whangarei Hospital.