A police officer has been stabbed in the chest at Frankland Prison.
The victim has been rushed to hospital where he is “conscious and talking”.
Durham Police said the officer, who is from another force, was attacked at about 11:00 BST while visiting the prison.
HMP Frankland in Durham City is a category A men’s jail, meaning it has the highest level of security.
A spokesman for the Durham force said: “A police officer, who was visiting the facility from an outside force, suffered a stab wound to the chest during the incident.
“The injured officer has been taken to hospital by ambulance, where he is described as being ‘conscious and talking’.”