LAST UPDATED 11.05pm A police operation remains underway in the Bay of Plenty after four officers were shot and injured.

They were shot during a cannabis raid near Edgecumbe.

LISTEN ABOVE: Newstalk ZB reporter Hannah Bartlett speaks to Marcus Lush from the scene

Two of the officers injured in the shooting have now been discharged from hospital.

Another officer has been transferred to Waikato Hospital in a serious but stable condition, while the officer who was shot in the hand will undergo further treatment at Waikato Hospital tomorrow.

Police Minister Judith Collins confirmed a shotgun was used, and all the officers shot were members of the Armed Offenders Squad, all of whom were fully kitted up.

No further shots have been fired since this afternoon and the scene will remain cordoned and contained overnight.

A lone gunman is believed to be holed up inside a rural property near Kawerau.

A woman who knows the gunman said she's been in contact with him today.

She said she's spoken with the man via text and has given him the third degree, telling him to give himself up.

The woman said he agreed to do that but wanted the support of family and friends to come out.

About 10 to 15 family and friends had gathered at police cordons.

SEE ALSO: Four officers shot, gunman told to give himself up

Acting Commissioner Mike Clement said members of the Armed Offenders Squad had surrounded the gunman's house.

Police confirmed the Defence Force has been deployed:

Police confirm our colleagues at NZDF have deployed 1x NH-90 tactical lift helicopter and 3x Light Armoured Vehicles (LAV) in a support role

— New Zealand Police (@nzpolice) March 9, 2016

A no-fly zone is also in place around the scene.

Prime Minister John Key commented on today's incident on Twitter:

My thoughts are with the officers injured in Kawerau today and with their families and colleagues.

— John Key (@johnkeypm) March 9, 2016

Mike Clement said they're planning a full investigation, but right now they have a man to arrest.

"For the time being, our emphasis is on containing this situation, which currently continues at this address and supporting the police staff who have been injured."

Police Commissioner Mike Bush has been briefed on the serious event after landing in Australia.

He will fly back to New Zealand overnight.

How things unfolded:

10.45am: Police hear three shots in the Otakiri area in the Bay of Plenty during an operation using a plane.

11.30am: Police cordon off a rural property on Onepu Springs Rd, Kawerau after another shot is fired at the plane, which is believed to have been searching for cannabis crops.

1pm: The Armed Offenders Squad arrive in Kawerau after being called out from Rotorua.

3.45pm: Police confirm three officers have been shot. A large police operation is underway at the property, where the gunman is believed to be holed up.

4.15pm: Two Rotorua officers arrive at Whakatane Hospital. A third officer is airlifted to Rotorua Hospital.

5.40pm: Police confirm a fourth officer has been shot.

6pm: Police hold a media briefing at National Headquarters in Wellington confirming they are only looking for one shooter.

7pm: Police announce a defence helicopter has been deployed to the scene along with three light armoured vehicles.

7.25pm: Police say a 3 mile radius no-fly zone has been established around the area.