They said the boat was well engulfed” in flames when the Deodar III arrived with firefighters on board.
All those on board were safe and would be transported back to land shortly.
A Coastguard spokesperson said they transported local firefighters from Howick.
A spokesperson from the Harbourmaster’s Office said crew from their team were on-site clearing the debris.
“The vessel that caught fire was a launch, and it has sunk.”
The launch was sitting to the east of Browns Island/Motukorea.
Police launched the Deodar after a launch caught fire in the Hauraki Gulf. Photo / Michael Craig
Smoke was seen billowing from the vessel on the Hauraki Gulf weather livestream. Photos showed large orange flames.
The Coastguard spokesperson said the pair were already safe in their dinghy when the police and Fire and Emergency arrived.
Smoke billows from a launch that caught fire in the Hauraki Gulf. Picture / supplied