Police took three men and a woman into custody.
Magnus Ranstorp of the Swedish National Defense College says the shooter is against mass immigration and "has to some extent the same themes as (Anders Behring) Breivik", who posted his 1,500-page manifesto online before carrying out his deadly attacks. In addition, 48 people have been injured and are now being treated at a Christchurch hospital.
"This shows that extremism is still flourishing in many places", she said.
Relief groups like the New Zealand Red Cross are already helping the community register missing persons, connect with loved ones, or mark themselves safe. In Scotland, the shooting of 16 students and a teacher in March 1996 prompted the banning of private ownership of handguns in the United Kingdom, and after the Port Arthur massacre where 35 people were killed in a series of shootings, Austrailia enacted widespread tightening of gun laws.
More than 40 people injured in the shootings are being treated in hospitals, Ardern said, and two of them remain in a critical condition.More news: Lisa Page: Yeah, Obama's DOJ Killed the Prosecution of Hillary Clinton
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Givealitte: This New Zealand-based crowdfunding platform is hosting a live campaign where people can donate for victim support.
The prime minister said early on Saturday that she had received "messages of condolence from around the world" and global leaders including Donald Trump, the United States president, who has been criticised for his hostility towards Muslims.
Beyond that, the New Zealand Police noted in a separate release that in 20 years, from December 1998 to December 2018, there were a total of 15 murders committed by someone, who had a firearms license.
Investigators were said to be trying to establish whether or not the other two people arrested were involved in the attacks.