THREE nurses were injured at the weekend when up to 24 patients housed in a secure unit at a mental health facility turned on them in an unprovoked attack.
The incident occurred at Baillie Henderson Hospital on Saturday shortly after 11.45pm.
The incident took place in the Ridley unit at the hospital - a detached, medium-security facility surrounded by high-level security fencing.
The three male nurses aged 31, 50 and 51 who were injured in the attack were transported to Toowoomba Hospital.
It is understood the 31-year-old man sustained serious injuries to his eye sockets and jaw as a result of the attack.
He will require further specialised treatment in Brisbane this week.
In a statement, Darling Downs Hospital and Health Service executive director of mental health Shirley Wigan said the attack had been unprovoked.
"The incident appears unrelated to metal illness and appears planned, occurring after a routine security inspection," Ms Wigan said.
"Senior medical and nursing management attended overnight (Saturday) and supported staff.
"Additional security staff was also deployed," she said.
Ms Wigan said Queensland police were investigating the incident and charges were expected to be laid against the patients involved.
"At no time was the external security of the building compromised," she said.
"The situation is now calm and controlled.
"De-escalation strategies are continuing and currently the unit is in lockdown."
Talking to The Chronicle yesterday, Darling Downs Hospital and Health Service chief executive officer Dr Peter Bristow said the circumstances surrounding the incident would be investigated.
"We cannot speculate about the patients' motivation for the attack," Dr Bristow said.
"There were a large number of patients involved.
"The incident took place in one unit of the hospital. There are a number of different units located at the grounds of Baillie Henderson," he said.
Ridley is the highest security rated unit located at Baillie Henderson hospital.
Queensland police confirmed investigations into the incident were continuing.