Four Corrections guards at Auckland Prison have been injured at the hands of prisoners during a serious assault this afternoon.
In a brief statement, police confirmed the attack took place about 4.25pm and said the victims "people sustained non-life threatening injuries".
Waitemata Police are investigating the incident.
Prison director Andy Langley confirmed four prisoners assaulted staff members at Auckland Prison this afternoon.
"Four staff have been taken to hospital for assessment and treatment. Every assault on staff is taken seriously, however their injuries are not life threatening.
"Our staff manage some of New Zealand's most dangerous people in a complex and challenging environment. No assault or violent behaviour is tolerated, and any prisoner who resorts to this behaviour is held to account.
"Our staff do an incredible job in some very challenging circumstances in order to keep New Zealanders safe."
The matter had been referred to police, and the prisoners involved would be held to account for their actions, Langley said.
He added that over 75 per cent of the prison population had convictions for violence in their offending histories, and more than 90 per cent had had a lifetime diagnosis of a mental health or substance use disorder.
Gang members were also disproportionately identified as responsible for assaults in prison.
Auckland Prison, known as Paremoremo Prison, is home to New Zealand's only specialist maximum-security prison unit and houses some of the nation's most violent criminals.
The prison holds men from minimum to maximum security risks and first opened in 1968.
Today's incident is not the first involving violence against guards.
On May 20 last year a guard was stabbed several times in the head with a shank (a makeshift knife) when officers were attacked by inmates coming back from the recreation wing to Bravo block.
Police charged the three prisoners who instigated the attack, but also investigated the force used by the guards in retaliation after their actions were caught on camera, which included a guard kicking one of the inmates in the head.
The prisoners all pleaded guilty to wounding with intent to cause grievous bodily harm and aggravated assault.
The three guards were charged with assaulting the inmate but were acquitted in September this year.