The latest violent incident at Perth's juvenile detention centre - the 10th in less than two-and-a-half months - has prompted the prison officers' union to blame it on the introduction of a rehabilitation program imported from the US.
Seven detainees were involved - three who jumped out of a window trying to escape - causing an estimated $350,000 to $400,000 trashing their unit on Saturday afternoon.
Guards used flash bombs and chemical spray to control rioting detainees.
The youths barricaded themselves in, removed bricks from walls and threw them at staff, broke every reinforced glass window and pulled panelling and cabling out of the ceiling, says the Community and Public Sector Union.
The Banksia Hill centre was locked down for three hours.
There has been a rise in incidents, including an officer having his arm broken and elbow dislocated by a 17-year-old detainee in mid-September and a riot that caused $150,000 damage on September 1.
"We've been saying for some time now that detainees' behaviour is getting worse, becoming more prone to violence and the staff - our members - are concerned about how long it will be before they end up in the firing line," union WA secretary Toni Walkington said.
The introduction of a more rehabilitation-focussed "Transformation Project" from the US and cultural change under Corrective Services commissioner James McMahon and deputy Rachael Green had been flawed and not properly explained to staff, she said, while other education and cognitive skills programs were cut.
The program was used in small prisons with handpicked detainees deemed suitable in the US, but at Banksia Hill was being applied to all 130-odd inmates, Ms Walkington said.
"It has not been made clear in concrete terms how all this fits together ... our members have been asked to behave and conduct themselves differently without really knowing how that works in the whole system," she said.
New rules introduced in July restricted officers' ability restrain or conduct strip searches and spit hoods were banned after the ABC TV Four Corners program showing guards abusing children in Darwin.
There is anger between some officers and the Department of Corrective Services.
Those officers believe they are now unsafe at work because of a regime which Ms Green has said "puts the young person at the centre of everything".
The department dismisses disgruntled guards as wanting to be allowed to go back to being prison officers rather than the softer-sounding "youth justice" or "group workers", Ms Green wants them to be called.
Mr McMahon said in a statement that importantly no staff or young people were injured, the incident was contained to a small area and there was never any threat to security at Banksia Hill.
Corrective Services Minister Joe Francis said he was confident Mr McMahon had the right team managing Banksia Hill.
I've turned up there unannounced twice in the last two weeks, walked around without a panic button, without a duress button, without an escort, walked around while 50-odd kids were kicking the footy around and I felt safer there than I do in some parts of Australia," he said.
- AAP