The suspects' ideology and preparation for the attack - Prime Minister Ardern described them as having "extremist views", but New Zealand's police commissioner said the man charged with murder was not known to intelligence services.
"I condemn the violent, extremist, right-wing terrorist attack that has stolen the lives of so many innocent New Zealanders as they went about their peaceful practice of worship at their mosques in Christchurch today", he added.
The suspect has been charged with murder while three other people have been held in custody.
Police found two explosive devices attached to the suspects' vehicles, which have since been disarmed.
The footage showed he was carrying a shotgun and two fully automatic military assault rifles, with an extra magazine taped to one of the weapons so that he could reload quickly.
He then walks outside to the street, where he shoots at people on the sidewalk. "Some were covered in blood", he said, adding that he joined the fleeing crowd and managed to escape.
This I want to assure people is to ensure that all our agencies are responding in the most appropriate way.
- One of the attackers - describing himself as Brenton Tarrant - appears to have live-streamed the attack on Facebook as he shot victims in a mosque.
AFP determined the video was genuine through a digital investigation that included matching screenshots of the mosque taken from the gunman's footage with images available online showing the same areas. Journalists experienced in verification techniques said it appeared to be genuine.
"Police alerted us to a video on Facebook shortly after the livestream commenced and we quickly removed both the shooter's Facebook and Instagram accounts and the video", Facebook said in a tweet.
First beta version official and available for download
Given the current smartphone design direction of more screen and less bezel, it's unlikely Google has dropped the idea completely. Maybe the Pixel 4 XL will inherit these, or maybe Google will upgrade them in a way.
"What has happened in Christchurch is an extraordinary act of unprecedented violence". "This is one of New Zealand's darkest days".
Forty-one of the people were killed at Al Noor Mosque, while seven died at Linwood Mosque. There were reports of armed police at a second mosque in the suburb of Linwood.
Hospitals said children were among the victims. At least one, though, is not believed to have had anything to do with the shooting.
He said he was inspired by Norwegian shooter Anders Breivik.
"There were bodies all over", he said.
Meanwhile, Cuomo ordered One World Trade Center's spire, the Gov. Mario Cuomo Bridge and the Kosciuszko Bridge be lit in blue and red tonight to show solidarity with the people of New Zealand and the Muslim community.
A spokesman for New Zealand's interior ministry said the video is likely to be classified as objectionable content under local law, and could be illegal to share. Friday is Islam's holy day.
Christchurch city council offered a helpline for parents looking for kids attending a mass climate change rally nearby. New Zealand Mosque Mass Shooting: Bangladesh Cricket Team Unhurt, Tamim Iqbal Tweets About Safety.
In a statement, Al Azhar University, Egypt's 1,000-year-old seat of Sunni Islamic learning, said the attacks had "violated the sanctity of the houses of God". "We have asked the team to stay confined in the hotel", he told AFP.
Italy's far-right Interior Minister Matteo Salvini voiced his "absolute condemnation" of the New Zealand killings, in a statement.
Dozens of people died and the city's historic cathedral was toppled in the disaster.