That alleged incident was in May and has preceded a "mass altercation" with staff on Monday evening in which the youth justice centre was locked down.

There are reports that staff members were taken hostage in Monday's incident, and afterwards seven were treated for injuries, first by paramedics at the scene and later at hospital.

Charges are likely to be laid following what was described in early operational advice as a "riot".

Visitors were turned away from Bimberi on Monday when it was placed on lockdown.

It took police two hours to secure the detention centre where there are roughly 15 young detainees currently housed.

The centre will come under scrutiny with an investigation launched by Worksafe ACT in addition to an ACT police investigation into the incident.

The ACT government has also commissioned an investigation into the incident from Peter Muir, a former director general of the Department of Juvenile Justice in NSW.

The review is expected to be complete by the end of October.

Children and Young People Commissioner Jodie Griffiths-Cook said that any incident of the type that occurred on Monday was concerning and she was keeping on it a watching brief.

Ms Griffiths-Cook said while the precursors to the incident were unclear, that she was interested in what could be learned from from what happened and how to avoid similar situations in the future.

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A Community Services Directorate spokesperson said operations at Bimberi were returning to normal over the course of a week.

The spokesperson said Bimberi's two official visitors, Tracey Lea Harris and Chris Redmond, had been provided daily updates and have a scheduled visit to the centre on Friday.

"The Community Services Directorate continues to ensure that staff and young people are receiving appropriate support following this incident. This has included on site Employee Assistance, social work support and medical support where required."

Opposition spokeswoman for youth and community services Elizabeth Kikkert said Bimberi needed to be a genuinely therapeutic rehabilitative space.

"As I said in the Assembly two years ago when addressing violence amongst detainees, 'Exposing them to trauma whilst detained will only result in their returning to our community more broken than they were when they first went in'.

"Local and international research has established what best practice in these kinds of facilities should be.

"Staffing levels need to be high enough. Staff need to be supported in order to avoid a high turnover. And staff need to have access to thorough and continuous training.

"To create a genuinely safe space for kids, staff need to be confident that they know how to appropriately de-escalate violent situations."