Six prison officers have been treated in hospital following an attack by a prisoner at Cork Prison at lunchtime.
The Governor of Cork Prison and the gardaí have begun separate investigations after a female prison officer suffered a dislocated finger, while a male colleague was knocked unconscious. He was head-butted and required stitches.
Four other prison officers received injuries which were described as being not serious.
It is understood they were attacked by a prisoner with a Perspex jug at around 1pm.
The situation in the prison was said to be calm but tense.
