Gun law reform within 10 days: New Zealand PM

At a news conference here, Ardern said her cabinet has agreed "in principle" on proposals to change the country's gun laws in response to the terror attack, but she stopped short of revealing what those changes might be, CNN reported.

Ardern said more details will be released once her cabinet "has worked through the in-principle decision" taken on Monday.

"As a Cabinet we were absolutely clear, the terror attack on Friday (March 15) was the worst act of terrorism on our shores," she said.

Echoing the Prime Minister's remark, New Zealand First leader Winston Peters, who also appeared beside Ardern, said: "This was a cabinet decision... The reality is after March 15, our world changed forever, and so will our laws," Peters said.

New Zealand First is part of the ruling coalition along with Ardern's Labour Party. It's the third-largest political party in the country and leans to the right on many issues, including immigration.

Ardern also confirmed there would be a review of security agencies' actions following the shootings at the Al Noor Mosque and the Linwood Masjid that also left over 40 others injured, The New Zealand Herald reported.

The review will look at what the agencies knew, or should have known, and whether there were any blocks to information-sharing.

It will also probe accused gunman, the 28-year-old Australian Brenton Tarrant's travel and use of social media.

Regarding the injured persons, health authorities said on Monday that nine people were still in a critical condition.

David Meates, chief executive of Canterbury District Health Board, said in a statement that two others would be released from hospital on Monday.

"There is still a four-year-old girl in a critical condition in Starship Hospital in Auckland," Meates said. "Her father has been transferred to Auckland and remains in a serious but stable condition."

Meanwhile, TradeMe, one of New Zealand's biggest internet auction websites, said in a statement that it will pull all semi-automatic weapons from its platform, following their use in the attacks.

The site said that it would halt the sale of semi-automatic weapons while it waited "for more clarity from the government".