UPDATED 5.01PM: An incident at a Hawke's Bay school which has left a boy in a critical condition is being treated by police as an accident.

The nine-year-old was found in the Taradale Primary School grounds at 1.15pm having difficultly breathing.

He's now in an induced coma and is being flown to Starship Hospital in Auckland.

Police say specific details of what happened won't be released until the police investigation is completed.