All frontline officers in Canterbury have been told to carry firearms until further notice.
The decision was made by the district commander, Superintendent John Price, today after two related incidents - in the suburbs of Wainoni on Saturday and Richmond on Tuesday night - in which officers were shot at.
One person has been taken into custody after the Christchurch shooting but police were still seeking one other person in relation to Wainoni incident.
All frontline police have firearms in their vehicles, but the Cantebury officers will also be carrying them in a holster.
In a statement, Mr Price said the decsion to arm all officers was not one to be taken lightly.
He said he believed it was necessary in this instance to ensure the safety of police staff and members of the public.
Police Minister Stuart Nash is backing the decision but said it did not mean that routine arming of police was on the horizon.
Mr Nash said he was told about the decision this afternoon.
He said it was a rare event and a temporary measure.
A woman living by the scene of the Richmond shootout, who didn't want to be named, supports the decision.
She was eating dinner when she heard "nine or 10 bangs" on Tuesday night, and said it gave her a fright.
Police officers shouldn't be left helpless in front of active shooters, she said.
"I think if somebody's got a gun and they're shooting at you - why should a law officer be helpless?"
She said she wasn't worried about the police abusing guns, because they can be held responsible more easily than other people.
"It's written down. We know who's got what [firearms] and where."
But other Christchurch residents had mixed opinions.
Elliot McLaren said he understood the need for police to keep themselves safe and the public safe.
"But we have seen what happens in places like America where firearms end up being used unnecessarily," he said.
"Guns kill people. That's what they do. That's what they're made for ... is that really what we want to do in this country?"