The category C prison was opened in 1988 and consists of eight units A prison officer is thought to have been knocked unconscious and another scalded with hot water in a disturbance at a prison in Cambridgeshire.
The ongoing incident at Littlehey, near Huntingdon, began at about 1700 GMT.
A Prison Service spokesman said: “A number of prisoners refused to return to their cells following an incident in which two staff were injured.”
The Prison Officers Association (POA) said up to 60 prisoners were involved in the disturbance.
The incident took place in the young offenders unit, it added.
The Prison Service spokesman said four or five inmates “were actively involved at the moment”, but could not say how.
“Prisoners are contained securely within one wing and do not have the run of the prison,” he said.
“Specially-trained prison staff are on their way.
“No fires have been reported and staff were treated at the prison.”
The spokesman said the injured staff did not need to be taken to hospital.
Colin Moses, national chairman of the POA, said he believed a female officer had been knocked unconscious.
He said: “They were trying to bring [the disturbance] back under control. Young offenders were acting in a violent way.”
A POA spokesman said the incident happened in the young offenders unit, where he believes 200 to 300 people are housed.
He said: “I believe one member of staff was scalded with hot water. The other was assaulted.”
They were both treated in the prison’s hospital, but have been discharged.
He added that there had been problems at the prison, including brawls and assaults, for the past 12 months.
Specialist officers are bringing the situation under control, he said.
The category C prison was opened in 1988 and consists of eight units.
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