Mr Bird said at that point the dog handlers intervened and attempted to take the offender to the ground.
"A firearm, believed to be a sawn-off shotgun, being held by the offender has then gone off seriously injuring the offender and also wounding one of the officers.
"Neither injury is considered to be life threatening and both the offender and the injured officer are currently undergoing medical treatment."
Mark Strongman of Huntly was shopping with his wife and granddaughter when he saw a van pull into the car park and a man jumped out armed with what Mr Strongman thought was a crowbar.
"It turned out to be a shotgun."
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The man tried to force a woman out of her car at the petrol bowser, but was unsuccessful.
"He had a woman by the scruff of her neck and he tried to haul her out. She had the good sense to hang onto the wheel, and not let go."
By this time police had reached the man and Mr Strongman heard a gunshot.
The man was quickly apprehended by at least four police officers, he said.
Mr Bird said the senior constable's actions were "right up there in the very highest echelons to apprehend an offender that we know is dangerous having access to firearms".
He said police would be recommending the senior constable of 10 years for a formal award.
Police earlier identified the man being sought in relation to the Kihikihi incident as 35-year-old Rangiriri man, Zeb Lee Sonny McCallion.
Mr Bird said no charges had been laid at this stage.
The offender was at Waikato Hospital undergoing treatment and police would be speaking with him upon his discharge, he said.
Detective inspector Karl Thornton said the victim was very shaken up and was being spoken to by police and victim support.
Mr Bird said although shaken she was "remarkably resilient considering the actions she was subjected to".
Commissioner Mike Bush said it was timely to reflect on the courage shown by the three officers who put themselves at risk to protect a member of the public.
"The bravery of these officers in tackling an armed and dangerous offender to keep innocent members of the public from harm is in the finest traditions of the New Zealand Police.
"Credit also goes to all of the other staff involved who helped to resolve this highly dangerous situation."