Manurewa residents are being asked to check their properties for a discarded knife after a stabbing left a 19-year-old fighting for his life.
Police say the man is in a critical condition after being stabbed in the neck during a fight between two groups in the Auckland suburb about 1am on Sunday.
They say the victim lost a lot of blood and received emergency first aid from police and ambulance staff before being rushed to hospital.
On Sunday night the victim was in a stable condition in hospital.
An 18-year-old man has been charged with wounding with intent to cause grievous bodily harm.
Part of Alfriston Road was closed for most of Sunday morning as officers searched for the weapon but is now open again.
Police say the stabbing is not believed to be gang related and they are still trying to establish whether the two men knew each other.