Police have stormed the roof of a juvenile justice centre, bringing to an end a violent 21-hour riot which left seven injured at the NSW Central Coast facility.
The riot broke out at Frank Baxter Juvenile Justice Centre at Kariong about 8.30pm on Sunday, with reports several inmates assaulted each other, NSW Police said in a statement on Monday.
Seven were injured and six were taken to hospital, including an 18-year-old who is in a critical condition with stab wounds and facial injuries.
Several inmates climbed onto the roof of the complex, with nine detainees surrendering over the course of Monday.
Finally, just before 5.30pm, riot squad officers accessed the roof where the remaining 11 detainees surrendered peacefully, NSW Police said in a statement.
"With nightfall coming, due to safety risks for all involved, we decided it was time," Superintendent John Gralton told reporters.
A total of 20 male detainees - aged between 16 and 20 - have been arrested and Supt Gralton said they would be charged with riot. The offence carries a 15-year maximum sentence.
The union which represents prison guards said the offenders stole keys from an officer and took garden tools, including a hedge trimmer and shovels from a maintenance shed at the state's largest juvenile justice centre.
Public Service Association general secretary Stewart Little alleged the group targeted sex offenders within the complex and described the riot as "nothing short of horrific".
"We have a juvenile justice system that has descended into chaos," he told reporters in Sydney on Monday.
He called for a judicial inquiry into the juvenile system noting it's not the first riot at the facility.
Families, Communities and Disability Services Minister Gareth Ward said the incident was unacceptable and the state government was treating it seriously.
He has asked for an urgent independent review, which will be conducted by former assistant commissioner Lee Shearer.
"The independent review will be in addition to plans already in place to establish a unit at Frank Baxter to manage high-risk offenders" he said in a statement.
"While the incident will be subject to a police investigation, actions that put the safety and security of staff and detainees at risk will not be tolerated."
Australian Associated Press