"CPR was performed at the scene, but sadly the boy was deceased,'' Wairarapa acting Senior Sergeant Rob Rackliff said.
"Enquiries so far indicate that the boy had gone out on the quad bike and was found by his father a short time later.''
The accident was the third quad bike fatality this year, according to the Ministry of Business, Innovation and Employment.
Neighbour John Pearce said the incident was "absolutely horrifying and tragic'', but he did not want to see any "recriminations about rural children''.
"These things happen in all walks of life.
"Many years ago people rode horses, and people fell off horses and died as well.''
Police have launched an investigation into the death and also referred the matter to the coroner.
A Labour Department spokesman confirmed tonight it had began making "preliminary enquiries'' into the accident.
A push by the Ministry of Business, Innovation and Employment was launched in September to coincide with the spring season, to reinforce safety messages to reduce quad bike injuries and fatalities.
Typically, five people die and 850 are injured each year in accidents involving quad bikes on farms, Department of Labour figures show.
While coroners regularly make recommendations about the use of quad bikes, they don't have the power to enforce that they are followed.
