The two officers had tried to stop the vehicle moments earlier but had lost sight of it.
Minutes later they discovered the vehicle had crashed – and a man allegedly opened fire on them with a long-barrelled firearm.
The man and an accomplice then allegedly fled the scene in a second vehicle.
One officer suffered fatal injuries and the other is in hospital in a stable condition, Police Commissioner Andy Coster told reporters tonight.
Earlier, Coster said a firearm had been recovered and two "people of interest" were being spoken to by detectives but he would not elaborate further.
"We are following strong lines of inquiry and our priority is to hold any offenders to account," he said.
A pedestrian is also in a stable condition in hospital after being run over in the incident in West Auckland this morning.
The family of the slain officer had been informed of his death and were "devastated", Coster said.
The alleged gunman's second vehicle had been dumped nearby and he and his alleged accomplice had fled. Police had recovered a firearm of interest.
Coster has issued a general arming order, which means all police in the Auckland district will be armed with firearms.
Ending the week with a very heavy heart after the death of a New Zealand police officer. To lose a member of the police...
Posted by Jacinda Ardern on Thursday, 18 June 2020 The shooting today - how it unfolded At 10:28am a vehicle of interest was spotted, Coster said.
Police attempted to stop it but the officers lost sight of it. They soon found it crashed on Reynella Drive the west Auckland suburb of Massey.
Police approached and a man got out with a long-barrelled firearm and allegedly shot at the officer, he said.
"Both officers were struck, one was killed," said Coster.
The injured officer is a man. He is in a stable condition.
The alleged offender got into another vehicle and allegedly fled the scene with another person.
The AOS was deployed, he said.
The second vehicle was found abandoned nearby.
The two police officers were shot in Reynella Drive in the west Auckland suburb of Massey. A cordon remains in place on Reynella Drive and an investigation team is working there.
"Our priority is to hold this offender to account," Coster said.
"I ask that you keep this officer's family in your thoughts, as their loved one will not be coming home tonight."
Coster said two people were being spoken to but he was not in a position to confirm "the full details" around them.
Police would remain under general arming orders until he was satisfied that the right people were in custody.
The vehicle stopped "had an alert on it" and that is why it was stopped, Coster said.
Police will not be releasing any information about the alleged offenders.
"I am not in a position to comment on the individuals... or their associations," Coster said.
He said there had been various things done today to locate the people involved. He would not be drawn on the specifics.
Coster said the AOS remained available to assist with investigations. Officers from across Auckland were working on the incident.
No further information would be released about the dead or injured police officer.
However, both were from the Waitemata District and their families were "devastated", said Coster.
He was joined at the conference by Waitemata District Commander Superintendent Naila Hassan.
Hassan has been based at the Henderson station, working with staff on the operation.
Hassan said everyone in her district was "devastated" but the incident was felt by "every member of the New Zealand police".
Police Minister Stuart Nash said the officer who died was a man who "dedicated his career to keeping us safe".
"Over 10,000 men and women have lost a valued colleague," he said.
"What an absolute tragedy. What can you say," Nash said.
St John confirmed three people have been taken to hospital. One of the police officers has died.
The Herald understands one of the shot officers was calling for help. He could be heard yelling that he had been shot and was bleeding.
Another of those hurt suffered serious injuries and the other is said to have moderate injuries.
It has been 11 years since a police officer was killed in the line of duty in New Zealand.
The last was Senior Constable Len Snee, who was shot dead by gunman Jan Molenaar in Napier in May 2009.
