A maximum security prisoner is in a Status 1 condition with life threatening injuries following a stabbing at Auckland's Paremoremo prison this morning.
Police say the incident started just before 10am when three inmates attacked one other in a cell.
The fight spilled out onto the landing of the cell block where a second inmate was also assaulted.
Both victims received a beating and were stabbed with home made weapons.
The attack ceased when prison officers intervened.