Police were called to the Korowai Manaaki facility in Wiri shortly before 6pm after eight youths climbed on to the roof.
RNZ's reporter at the scene said occasional shouting and banging could be heard, and some of the youths were throwing hand signs and posturing for media at the scene.
One was also seen throwing a ventilation cover that had been wrenched off the roof.
Oranga Tamariki acting deputy chief executive of youth justice services and residential care Iain Chapman said four of the young people had come down overnight and this morning, but four remained on the roof.
"Police continue to monitor the situation, and we can confirm there are no concerns for public safety and the young people are still within the facility," he said.
"An operational review will be undertaken to determine the circumstances that led to the incident."
Chapman said many of the young people in custody in youth justice facilities had committed serious offences motivated by a range of factors, including peer pressure, notoriety and adrenaline.
"It is likely they participate in serious incidents once in custody for similar reasons."
It was the second protest at Korowai Manaaki this year - seven teenagers were charged after spending the night on the roof in October.
