A white supremacist suspected in shootings at two mosques that killed 49 people during midday Friday prayers posted an anti-immigrant manifesto online and apparently used a helmet-mounted camera to broadcast live video of the slaughter on Facebook.
Outside the court, the son of 71-year-old Afghan victim Daoud Nabi demanded justice for his late father, who believed New Zealand to be a "slice of paradise".
"There is one charge of murder brought at the moment, it is reasonable to assume that there will be others", said Judge Paul Kellar.
A day after he gunned down 49 people who were attending Friday prayers in two mosques in Christchurch in New Zealand, the main suspect Brenton Harrison Tarrant was charged with one count of murder Saturday.
"The mere fact. that this individual had acquired a gun licence and acquired weapons of that range, then obviously I think people will be seeking change, and I'm committing to that", the Agence France-Presse quoted Ardern as saying.
"There are many, many victims of this tragic event and we are giving every possible support to them".
He livestreamed 17 minutes of the rampage at the Al Noor mosque, where, armed with at least two assault rifles and a shotgun, he sprayed worshippers with bullets, killing at least 41 people.
Thirty nine people remain in hospital, 11 of whom are in critical condition in an intensive care unit.
Families of the Sandy Hook victims were recently given the green light to sue United States gunmaker Remington for knowingly marketing a military grade weapon that is "grossly unsuited" for civilian use and has become the gun of choice for mass killings.
New Zealand police commissioner Mike Bush said two of those in custody were arrested at a cordon, and that officers were working to establish whether they had had any involvement in the incident.
Crusaders chief executive Colin Mainsbridge said: "Yesterday's horrific attacks have left us all feeling stunned".
Acting Deputy Police Commissioner Mick Willing says Tarrant was only known to police for "minor traffic matters".
Before the attacks, New Zealand was widely considered a placid, scenic land that doubled as the home of the hobbits in Jackson's cinematic versions of J.R.R. Tolkien's classic fantasy novels. "There have been attempts to change our laws in 2005, 2012, and after an inquiry in 2017".
She firmly added in a statement: "Our gun laws will change".
During the emotional service the woman all held a placard with the words: "Peace will save the world #Solidarity with New Zealand mosque victims".
- AP In this photo released by New Zealand Prime Minister's Office, Prime Minister Jacinda Ardern speaks to representatives of the Muslim community, Saturday, March 16, 2019 at the Canterbury Refugee Centre in Christchurch, New Zealand.
"It's the time for change", said Ardern.
Mr Bush, who had earlier called the attack a "very well-planned event", said the suspect was not known to police either in New Zealand or Australia.More news: Reputed Boss Of Gambino Crime Family Gunned Down In New York
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