Police say the incident in which an officer was run over by a gunman, who later died after being shot, was "dynamic and extremely fast moving".
The police officer who was run over is in a stable condition, awaiting surgery at Christchurch Hospital.
Police had been called to a Bangor Road property where a man had been threatening a family member and shooting at the door of the house.
On arrival, officers saw a man getting into a vehicle and leaving the property. Two officers attempted to stop the vehicle using road spikes.
As the officers were laying the road spikes, the man drove the vehicle toward one of the officers, hitting him and causing a serious leg injury, Superintendent John Price said.
Police then shot at the driver, he said.
The man was found dead in his car on Bangor Rd a short time later.
Police said the injured officer was in hospital with multiple fractures.
Superintendent Price said the investigation is ongoing as police continue to speak to a number of witnesses.
"This was a dynamic and extremely fast moving incident," he said.
Mr Price said he had visited the injured officer in hospital and that he was in a lot of pain.
He said the family of the deceased have been offered support.
"This is a terrible situation for all concerned."
Police Minister Stuart Nash extended his sympathies to the family of the deceased and best wishes to the injured officers.
"This is still an active Police investigation and I will refrain from further comment on the specifics of the incident.
"However, my condolences go to the family of the man who has died," he said in a statement.
"I also want to acknowledge the impact this will have on the officer who was seriously hurt.
"He has suffered a traumatic injury while responding to a fast-moving and dangerous incident where the public reported shots had been fired.
"He will take some time to recover and Police will offer whatever support they can to ensure his full recuperation," Mr Nash said.
A section of road remains cordoned-off.
The matter has been referred to the Independent Police Conduct Authority.