A man has been stabbed and his sister attacked in an incident in the Hauraki Plains town of Paeroa.
The police say the 25-year-old man and his sister, aged 20, were walking through a park when they got involved in a verbal altercation with three men and a woman.
They say the brother and sister were then followed to the corner of Railway Road and George Street where the man was stabbed with an unknown object at least three times. His sister was punched.
The man was flown to Auckland Hospital in a critical condition and had surgery on Friday morning.
Police are appealing for any witnesses to come forward.