The government has been urged to increase therapeutic services at the facility to help manage the complex needs of the young people.

Detainees attacked staff with an improvised knife and a computer while one managed to steal a guard's keys, according to a review into the August 27 incident by independent assessor Peter Muir.

Staff were able to secure four of the five teens involved in the incident. But the fifth escaped and used a set of keys to free another inmate.

Seven staff had to attend hospital after the escape attempt. Two staff members are yet to return to work.

Mr Muir said many of the young people had histories of abuse, neglect, exposure to family violence, and mental health issues.

Despite this, they did not have adequate access to therapeutic services.

"I record this not to excuse the actions of these young men but to demonstrate the complexity of cases that staff and management face on a day-to-day basis," he said in the review.

Mr Muir said the most credible theory on the incident was that it was started and led by a known young person in an attempt to avoid extradition to NSW.

"I found no evidence that this was known to any staff member prior to the incident," Mr Muir said.

He said there was no protocol at the time with police for assisting in such situation.

Mr Muir made 27 recommendations in his review, including calling on the government to increase staffing levels to manage inmate classification and intelligence functions.

Mr Muir could not find any significant failing in the management of the young people's behaviour and said staff responded with a high degree of professionalism, courage and teamwork.

The impact of staff absences should be investigated, he said, but could find no evidence short staffing played a role in the incident.

There was one breach of security procedures identified in the probable failure of a staff member to secure their keys.

Mr Muir said the work health and safety system was not working as well as it should.

Minister for Children, Youth and Families Rachel Stephen-Smith said immediate action was being taken in response to the review.

Three additional full-time staff members will be hired - including a principal practitioner to strengthen trauma-informed, therapeutic treatment - while building works at the centre will be completed.

A consultant will also be hired to review and update emergency operating procedures and to provide negotiation training.

"I commend the staff who were involved in this incident for their professionalism, courage and compassion, and thank all Bimberi staff for the work they do every day to support complex young people with a focus on rehabilitation," Ms Stephen-Smith said.