Two police officers who were shot near Kawerau in the Bay of Plenty have now been discharged from hospital.
But a third, and more seriously injured officer, remains in Waikato Hospital. And a fourth officer injured in the shooting will undergo further treatment at the same hospital tomorrow after being shot in the hand.
The police say the person who shot and wounded the officers is acting alone and still inside the rural property at the centre of a siege.
Police said their operation would continue through the night, and no further shots had been fired.
What we know:
* Four police officers have been shot; two have been discharged from in hospital. A third more seriously injured is in Waikato Hospital. The fourth was shot in the hand and is receiving treatment
* Armed police have surrounded a rural property, where they believe the sole offender is holed up
* The incident was sparked after shots were fired at aircraft taking part in a cannabis operation
* Residents have been warned to avoid the area, but police say there is no risk to the public
* Police Commissioner Mike Bush is returning to New Zealand from Australia tonight.
RNZ's Diego Opatowski is at the scene in Onepu Spring Road.
He said family and friends of the man holed up in the house were gathered at the cordon.
He said they were unhappy and did not want to be photographed so media was keeping its distance from them.
Look back at RNZ's live coverage to see how events unfolded
A woman who is in lockdown on Hogg Road which is inside the police cordon with her parents and her son and heard guns shots this afternoon.
"I have heard shotguns going off but I'm not certain where they were going and I have seen four helicopters fly in and out of the road since about half past three this afternoon.
"I'm hoping I am, but I'm kind of praying at the same time that it's going to end soon and everyone's going to be fine."
She said she was keeping an eye on her neighbours.
"We're pretty safe and secure. We're like a farming community, we've always got each other's backs and every now and then you hear the odd gun fire but that would be either going for a rabbit or a possum; nothing out of the ordinary. But for some weird reason this is out of the ordinary," she said.
Police have called in a Defence Force NH-90 tactical helicopter and three Light Armoured Vehicles to assist with the arrest of the alleged gunman.
A no-fly zone is now in place around the scene.
Police first confirmed details of the incident on a rural property near Kawerau, in the Bay of Plenty, shortly after 4pm.
Deputy police commissioner Mike Clement said there was apparently only one offender and that person was still in a house which had been cordoned off on Onepu Spring Road outside Kawerau.
Mr Clement said police had been in the area at 10.45am for a cannabis recovery operation when three shots were heard.
The police cordon at Onepu Springs road this evening. Photo: RNZ / Diego Opatowski
Watch the police news conference here:
At 11.30am another shot was fired at an aircraft and police then cordoned off the Onepu Spring Road property.
The Armed Offenders Squad arrived at 1pm and at 3.45pm police received confirmation three officers had been shot. Shortly after 5pm a fourth officer was also reported injured.
Defence force chopper being loaded at the Royal New Zealand Police College, Porirua. Photo: Angelique Eagar
Mr Clement said support was being offered to the injured officers' families and there would be a full investigation post the ongoing operation. The IPCA will be advised.
He said police had the area around the house contained but he did not want to say too much as the offender "may be watching on his own television".
Deputy police commissioner Mike Clement briefing the media this afternoon. Photo: RNZ
Police were urging the public to avoid Onepu Spring Road.
A kaumatua from Hahuru marae, Hori Raerino, said the situation had been unfolding at a house nearby.
"There's a lot of cars, a lot of police presence just down the road.
Onepu Spring Road Photo: GOOGLE MAPS
He first heard a shot - he believed from a high-powered rifle - at 10am.
"I got a fright as when I went down there they were standing there with guns."
A Kawerau resident, who did not want to be named, said there had been a heavy police presence in the area since midday. He had seen at least 10 police patrol cars, two ambulances on standby and up to 15 armed police officers.