Counsellors will be at King's College in Auckland again on Tuesday as students and staff grapple with the loss of another pupil.
The teenager died in hospital on Monday after being admitted in a critical condition.
Earlier this year, a boarder was found dead in his bed and last week a student died after drinking at a party.
King's College says the Ministry of Education's traumatic incident team has been at the school following the latest death to guide it on how to support students and staff.
Headmaster Bradley Fenner says a support centre, manned by chaplains and counsellors, has been established in the school's chapel.
Students bewildered - chaplain
Chaplain Warner Wilder says the deaths of the three young men have left King's students struggling with a sense of bewilderment.
He says the three boarders' deaths are unrelated and college staff are doing their best to keep the school routine as normal as possible under the circumstances.
Mr Wilder says some students have been really badly affected. One or two of the boarders have been taken home.