Three of the six children who climbed on to the roof of Western Australia's Banksia Hill Detention Centre have been moved to the notorious Unit-18, a centre within the maximum security adult prison; Casuarina.

The six youths, aged between 12 and 17, got on to the roof of Banksia Hill on Monday afternoon. Three came down over night, with the remaining three coming down some time before 8am Tuesday morning.

Footage shows the children throwing objects such as vents from the roof, with one spraying a fire extinguisher. A WA Department of Justice spokesperson said no one was injured during the incident.

Justice and child welfare experts have long called for Unit-18 to be shut down.

In October 2023, WA's Children's Court president Hylton Quail slammed the facility in the wake of the death in custody of 16-year-old Yamatji boy Cleveland Dodd, who was found unresponsive in his Unit 18 cell days before his death in hospital.

Judge Quail condemned the facility while sentencing of a 15-year-old who was detained there on remand, saying the environment made the boy more of a danger to the community when he came out than before he had gone in.

"Those who administer Unit 18 do so with impunity," he said,

"Those conditions in Unit 18 and the way that you have been treated whilst you have been in custody have been of no rehabilitative effect. You have therefore been released into the community more dangerous than when you went in."

Aboriginal children are dramatically over-represented in Banksia Hill, and conditions within the centre have long been criticised widely by legal experts and Indigenous advocates.

A class action against the WA Government regarding Banksia Hill is underway involving some 500 individuals.

Megan Krakouer, who has played a key role in organising the legal action, told National Indigenous Times: "Let's be absolutely clear: children in Banksia Hill Detention Centre are still being mistreated, and their fundamental human rights are being violated every single day."

"The conditions remain dangerous, degrading, and completely unacceptable," she said.

"The Government must release robust, comprehensive, and independently verified data on all critical incidents: every instance of self-harm or attempted self-harm, every use of force, every restraint, every lockdown hour, every so-called 'critical intervention'.

"For too long, these numbers have been buried, watered down, or delayed, and that lack of transparency has allowed ongoing harm to remain hidden from public scrutiny.

"Banksia Hill is still in crisis, and until the Government is willing to confront the real data and deliver real reform, kids will continue to suffer behind those walls," she said.

WA Corrective Services Minister Paul Papalia questioned the risk analysis previously carried out on the young detainees

"You'd have to question whether or not the multi-disciplinary team threat analysis was good enough," he told the ABC.

"Also, pretty clearly there's been some tactical failures with the response."

WA Commissioner for Children and Young People Jacqueline McGowan-Jones said the detainees needed more support.

"One of them had a very distressing phone call yesterday. He didn't know how to behave, he probably got frustrated and then angry," she told the ABC.

"We critically need quality psychological and psychiatric supports for the detainees that is available 24/7 on site."