Staff were attacked with an office computer and an improvised knife during a mass escape attempt at Bimberi Youth Justice Centre, a report has found.
ACT Parliament was on Tuesday told the August 26 incident - previously described as a riot - began when five young people from one unit tried to overpower staff in an attempt to get their keys and escape.
An interim report from independent assessor Peter Muir found that during the incident, one staff member was injured by the office computer which was used to attack him.
A "sharp, improvised weapon" was used to inflict further wounds on at least two other staff members, his report tabled in Parliament said.
There were 15 young people in Bimberi Youth Justice Centre and 11 staff on duty on the night.
Minister for Children, Youth and Families Rachel Stephen-Smith told ACT Parliament after the five inmates tried to overpower staff, they managed to secure all but one of the inmates in the cabins.
The one young person remaining free managed to take the keys, leave the unit and make his way to another unit in the centre where he released one other young person, Parliament heard.
Police arrived soon after and negotiated with the two young people who were in the facilities area.
Ms Stephen-Smith said the assault on staff was "significant", with seven attending hospital.
She praised three young people in the centre who actively decided not to participate in the incident.
Mr Muir's report indicated the centre director used "sound judgment" and her decisions in managing the incident were correct.
He said the incident was "at the more serious end of what you would expect to see in a youth justice centre".
"Staff responded to this event with a high degree of professionalism, courage and teamwork," Mr Muir said in the report tabled in Parliament.
Mr Muir found Bimberi needed to improve its capacity to assess and manage emergency risks.
The centre also needed to ensure staff had refresher training on the use of force when it is due, and it needed to develop a protocol with police for when assistance is required.
Mr Muir said there was a need to further discuss the adequacy of therapeutic support.
He said the work health and safety system was not working as well as it could, with a lack of engagement from stakeholders.
In his report, Mr Muir noted that many of the inmates had mental health conditions.
He said he noted this not to excuse their actions but to demonstrate the complexity of cases staff faced.
"It is too early to provide recommendations until I have completed further investigations of the matters at hand and assess the various options that I see in need of remediation," Mr Muir said.
"I would note that in relation to a number of these issues, Mr Muir also finds that, based on the evidence he has reviewed, the areas for improvement or discussion did not necessarily adversely impact on the evening's events," Ms Stephen-Smith said.