Another said "I feel sick, I feel shattered.... someone came to work today to save the lives of others and they are going home in a box."
"This will be the first plaque on the (remembrance) wall since 2009.
"We've got to find this (offender)."
"We thought despite an increase in firearms on the streets we were holding out own... but we knew it was volatile.
"We took 60,000 guns off the streets in the buy back and then to have the first death in 11 years - a police Officer gunned down, gunned down and slaughtered.... it's absolutely awful."
PM on the officer's death
Ardern says 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. My condolences go to them and to their Police whanau," she said.
'A man who dedicated his career to keeping us safe'
During a standup at the Hastings Police Station Nash said the officer was "a man who dedicated his career to keeping us safe".
It was "devastating news" he said, a "grey day across the whole country".
Nash said it was "gutting" that a member of the NZ police family had been shot dead.
"What an absolute tragedy. What can you say.
"Over 10,000 men and woman have lost a valued colleague."
Police Association President Chris Cahill says the killing of an officer and the injuring of another officer is an absolute tragedy for those involved, their families, colleagues, and all New Zealanders.
"We all know being a police officer is a risky job, but officers live with the expectation that they will go home at the end of their shift. Their families live with that expectation too, and they have every right to see their loved ones home safely," Cahill said.
"The association's role is now to wrap its support around these families, friends and colleagues and make sure we are there for them in the difficult times ahead.
"I want them to know that while we can't even begin to understand the pain they are now faced with, police is a whanāu of 14,000 plus and it is a whānau that, regrettably, has had to pull together in similar circumstances in the past and will do so again."
Cahill says this incident demonstrates the risks to officers in everyday routine policing, and highlights the dangers of the proliferation of firearms in the hands of criminals.
"It is an absolute tragedy that the very people who run towards danger to keep us all safe, can end up paying the ultimate price in the line of duty," he said.
"It is now the job of colleagues of the officers caught in this Massey event to find the person responsible, and I have every confidence in their professionalism and ability to do that as soon as possible."
The association also wishes a speedy and successful recovery to the officer who is hospitalised with serious gunshot injuries, and to the member of the public who was also injured by a vehicle in this appalling and heartbreaking event.
Earlier Nash said he was "heartbroken for the family and colleagues of the officer who has died today".
"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.
"We have another officer injured by gun fire and a member of the public has also been injured by a fleeing offender. Our thoughts are with them.
"I have spoken to the Commissioner of Police this morning to ensure that he and his senior commanders have all the resources they need to respond. Police will provide further updates as they are able to.
"The officers' families and colleagues also need all the support they can get. This will take a toll on them in the days and weeks ahead.
"I want to thank those who were first on the scene to help and acknowledge the health professionals who worked to treat the officers.
"In the history of New Zealand policing since 1890, 22 officers have been shot and killed on duty, most recently Senior Constable Len Snee in Napier in 2009. Since 2002, 15 officers have been wounded by firearms.
"Massey has a strong community spirit and this will be frightening for the locals caught up in this. I urge members of the public to follow instructions from Police and to keep themselves safe," said Nash.
Earlier:
Two officers were shot and a member of the public was hit and injured by a vehicle after police performed a routine traffic stop on Reynella Drive in Massey.
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.
The offender fled the scene in a vehicle and police have a large presence actively searching for the person.
Cordons are in place and schools in the immediate area have been advised to lockdown.
Police have advised all members of the public to avoid the Massey area, in particular the areas around Don Buck Road, Waimumu Road, Hewlitt Road and Triangle Road.
Elaine Taniela, who lives near Reynella Drive, was at home when she heard three distinctive sounds she now believes were gunshots.
Taniela said her father's friend, who had been coming over to their house at the time, described harrowing scenes as he drove down Reynella Drive heading towards Triangle Rd.
"He was shaking telling us," she said.
"As he neared the first roundabout (near Gallony Avenue) he saw a cop on the ground. "He said it looked like he was having a seizure. He was shaking."
It has been 11 years since a police officer was killed in the line of duty in New Zealand.
The last police officer to be killed by a criminal act was Senior Constable Len Snee, who was shot dead by gunman Jan Molenaar in Napier in May 2009.