The rangatahi were not doing anything wrong, nor being arrested.
Further RNZ reporting by Te Aniwa Hurihanganui suggested the practice was far more widespread than just in Wairarapa.
Police subsequently launched a review, and as a result of that, officers will no longer take pictures or fingerprints of young people unless they have been arrested or are being summonsed.
They will delete all photos of young people already taken on police-issued phones.
From now, when a picture is taken, only official cameras or photographers should be used.
At a pinch, a mobile device can still be used by officers, but the photo must be deleted off the phone once it has been uploaded into the police's national intelligence database.
Barrister Marie Taylor-Cyphers said there was the risk it could lead to more Māori being arrested, rather than just being given a warning.
"If a police officer, in the course of their investigation, needs to for some reason identify the child by photographing them, then they're going to be incentivised to place that child under arrest more readily than previously."
Police deny there will be an increase in Māori arrests as a result, calling the changes a procedural issue.
Taylor-Cyphers said the way the policy was worded appeared to give police permission to photograph young people in a wider range of circumstances than adults.
Police said the law allowed them to take pictures of people in custody.
But Taylor-Cyphers said the new rules also let police snap photos of young people under summons - which often happened for lower level offences like traffic or driving infringements - and the policy needed to be tightened up.
Dr Karaitiana Taiuru, who has completed a PhD on indigenous ethics in data collection, described the changes by police as a "huge step forward", but also worried it could lead to more rangatahi facing charges.
Taiuru said we would have wait and see how the policy was implemented.
"In a year's time, it would be really interesting to see the statistics on ... how many Māori youth were arrested for low-level crimes rather than non-Māori youth.
"And then compare the amount of photos taken of Māori youth compared to non-Māori youth."
The full findings from the police's internal review are expected early this year, as is a joint Independent Police Conduct Authority and Privacy Commission inquiry.
