Prime Minister Jacinda Ardern is devastated following the death of a police officer today.

The police officer, understood to be a male, died after he was shot in Massey, west Auckland following a routine traffic stop on Reynella Drive.

Another officer was also shot and an innocent pedestrian was run over by the fleeing driver following the incident this morning.

Ardern said the news of the police officer's death was "devastating".

"To lose a police officer is to lose someone working for all of us, but also a family member, someone's loved one and friend," she said.

"My condolences go to them and to their Police whanau."

The officer who died was a man who "dedicated his career" to keeping the community safe, Police Minister Stuart Nash said.

The Herald understands one of the officers shot was calling for help and could be heard yelling he had been shot and was bleeding.

Another of those hurt suffered serious injuries and the other is said to have moderate injuries - all three were taken to hospital, St John confirmed.

It has been 11 years since a police officer was killed in the line of duty in New Zealand.

• 'The worst news police can get': Commissioner on officer shot dead in Auckland

The last was Senior Constable Len Snee, who was shot dead by gunman Jan Molenaar in Napier in May 2009.

The offender fled the scene in a vehicle and police have a large presence actively searching for the person.

It is unclear if the offender has been apprehended by police.

Police Association President Chris Cahill said officers knew its a risky job, with policing involving all sorts of activities.

"We've seen how routine incidents can be risky," Cahill said, speaking at Hastings Police Station a short time ago.

Nash was alongside Cahill at the police station and said the also said the news was devastating, labelling it a "grey day across the whole country".

Earlier today, the Police Minister said he was heartbroken for the family and colleagues of the officer who died.

"We want all our police officers to get home safely at the end of every working day. This is a tragic day for our police family," he said.

"We have another officer injured by gunfire and a member of the public has also been injured by a fleeing offender. Our thoughts are with them."