Two people in critical condition are being flown by rescue helicopter to Auckland City Hospital after a boat with five people on board flipped on Tairua Bar near Pauanui. 

A third person has been treated at the scene for minor injuries, a St John Ambulance spokeswoman said. 

Police confirmed five people were on board the boat and all are accounted for. 

Multiple ambulances and rescue helicopters were sent to help soon after 2.30pm. 

A witness said three rescue helicopters had landed in the area, a popular Coromandel holiday spot, and the Coastguard was also involved. 

"Coastguard boat still out in water towing boat upside down - it had turned over but when they got person out it flipped again and went back out to sea." 

Video shot at the scene showed people holding up a sheet as ambulance officers worked near a surf lifesaving IRB. 

It also showed a semi-submerged boat near shore. 

They had one ambulance at the scene in Vista Paku, along with to managers, the St John spokeswoman said. 

Another ambulance, a rapid response unit and two rescue helicopters had also been sent to help. 

Emergency services were alerted at 2.37pm. 

The incident comes two days after a boatload of people had a lucky escape when rough seas flipped their vessel on Tairua bar. 

Video provided to the Herald showed the Coastguard towing the submerged, upside-down boat before a crowd of people helped right it. 

The Pauanui surf lifesaving club had picked up the boat's passengers, none of whom were injured, but the boat had been upturned and was on the inside of the bar, Andrew Gibson, president of the Tairua-Pauanui Coastguard unit, said. 

"It is a treacherous bar, especially at low tide." 

Low tide is at 4.12pm today. 

More soon.