The group of four had been contracted to work in the Woomera Detention Centre in South Australia, but would normally be working at the Junee Correctional Centre.

Originally, Junee Correctional Centre general manager Col Kelaher reported only "one member of our staff employed at the Woomera detention centre received slight injuries, but the other ... employees including those from Junee, were not injured".

Though, an inside source involved in the riots claims a total of four guards from the Riverina were left with broken bones and a concussion.

They were among 13 guards who were injured in the riots that engulfed the centre on the day in question. Friday marks 20 years since that harrowing day.

It is understood about 80 asylum-seekers became violent inside the centre, attacking guards with weapons including crudely-made spears.

At the time, a guard from Wagga spoke to APP and described his attackers as "acting like wild animals".

Over three days, the detainees went on to tear down barbed wire fences in their attempts to liberate themselves and the other 800 people living inside the facility.

Additionally, the rioters set six buildings on fire, gutting the facility's school and recreation room.

While charging the the perimetre fence, the detainees were eventually subdued by a mobile water canon. Guards also administered tear gas on the crowd.

Following the blow up, 25 of the inmates, who were believed to have incited the riot, were trucked seven hours to the Adelaide Remand Centre.

Their transport were surrounded by police guards and security staff.

It is believed the detainees were incited to violence after being notified that they would face deportation