Police Commissioner Mike Bush has announced the process of identifying all 50 victims has been complete and next of kin have been advised.
He said authorities were working hard to open up the Linwood mosque and Al Noor mosque in Christchurch where the shootings of worshippers took place.
In light of Prime Minister Jacinda Ardern's announcement of the banning of all military-style semi-automatic firearms and assault rifles, Mr Bush said there would be a grace period for those in possession of these.
"We'll be working with everyone to take those firearms off them and into a place of safekeeping," he told media this afternoon.
"The first step is to do it voluntarily, we'll then be working to ascertain if they haven't complied and those people will be in all likelihood prosecuted," Mr Bush said.
There were about 250,000 firearm holders in New Zealand, he said. People wishing to surrender their firearms must first contact police - either online or by phoning at 0800 311 311.
Referring to CCTV footage of the mosque attacks, Mr Bush said: I've seen that footage. It's really disturbing. I don't think that kind of thing should be in the public domain."
He said police were still in a state of high alert across the country.
An update from David Meates, CEO of Canterbury District Health Board
Twenty-eight people who were injured in Friday’s shootings are still in Christchurch Hospital, with six remaining in critical condition in intensive care, Mr Meates said.
One more person was well enough to be discharged from hospital with appropriate community supports, and two others have improved enough to be moved from ICU to other wards, he said.
One four year old girl is still in a critical condition in Starship Hospital in Auckland and her father is in a stable condition in nearby Auckland City Hospital.
"The people injured in the mosque attacks are still our priority for specialist care, which for some includes follow-up surgery and although we are closer to being able to resume our planned surgery schedule we will still need to postpone some surgeries for the remainder of this week to free up theatre space and surgical teams. Anyone affected by rescheduling will be contacted individually, and we will be apologising for the delay and thanking them for their understanding.
"Christchurch Hospital is still exceptionally busy and we appreciate your support in reducing the demand for acute services such as the Emergency Department at this time. Although general practice has had a significant addition to their workload because of the ongoing measles outbreak in Canterbury, they should always be your first point of call for non-urgent care – call your normal GP team’s number 24/7 and after hours a nurse will advise you what to do and where to go," he said.
- Reporting by RNZ and NZME.
