Police will make inquiries on behalf of the coroner. The coroner would release their findings “in due course”, the spokeswoman said.
The boy’s family needed privacy while they dealt with their loss, she said.
The two boys were digging tunnels in the sand during a family picnic when a sand dune collapsed and buried them on Sunday.
The boy’s father encouraged people to pray for the other boy involved.
The pair were flown to by flown by rescue helicopter to Starship Children’s Hospital in critical condition from Medlands Beach.
One of the boys, aged 14, was found with his legs sticking out of the sand and was pulled out with the help of a vehicle, Stuff reported.
The other, a 12-year-old, was completely buried and was not breathing by the time he was extracted.
Beachgoers and emergency services, including staff from two rescue helicopters, scrambled to dig the boys out.
The devastated community of Great Barrier Island has banded together and a Givealittle page has been made to support the family of the boys.
The page describes a beautiful day at the beach which turned into a tragedy.
“Please, please, if you can, donate to this tragic cause - support the boys through their battle, support the whānau through theirs.
“The whole community of Great Barrier Island is devastated and banding together with solidarity and strength of love to support them,” the page’s creator Aroha McGeady wrote.
The page had raised $55,145 at the time of publication.
“Our thoughts are with the boys and their families,” a rescue helicopter spokesman said.
Great Barrier Local Board chair Izzy Fordham earlier said that she was “very aware” of the incident and told the Herald it was a “horrid time”.
Great Barrier’s sand dunes extend across the eastern coast of the island, from Medlands to Whangapoua.
One Great Barrier Island resident said there were ocean-side sand dunes that were left exposed after the recent severe weather events, and locals were worried about them.