A man is in an induced coma in Auckland Hospital after he was attacked in a North Shore toilet block last night.
The man was found in the block in Belmont about 8.30pm, Senior Sergeant Grant Tetzlaff said.
He was taken to Auckland Hospital in a critical condition.
A scene examination was being carried out today. It was not yet known whether a weapon was used in the attack.
"By this time tomorrow we should have a better idea of what has occurred," Mr Tetzlaff said.
Mr Tetzlaff said police are yet to speak to the victim, who remains in a critical condition.
"He's having some surgery either this evening or late this afternoon and he's in a medically induced coma at Auckland Hospital."
Mr Tetzlaff said police spoke to a number of witnesses last night and were interested to speak to anyone who was in the area around 8pm.