Police say it is sheer luck that no-one was killed after a 13-year-old boy was shot in the shoulder by his 11-year-old cousin at a property near Turangi early on Saturday.
The teenager was rushed to Waikato Hospital with moderate injuries and is reported to be in a stable condition.
Detective Roger Whale said initial inquiries indicated the boy was shot at a rural address at Korohe, north of Turangi, where family members were present.
The injured boy was taken back to a Turangi address where the alarm was raised. Det Whale said it appeared the children gained access to a loaded .22 calibre rifle and it was "sheer luck" that no-one was killed.
Police have spoken to the boys to determine how the firearm came into their possession.
Det Whale is warning that adults should be storing firearms and ammunition safely.
"Firearms should only be loaded when they are ready to be fired," he said.
Police would like to hear from anyone with information about the Korohe incident.
It is not known whether any charges will be laid.
