Police Commissioner Mike Bush declined to comment on whether it was an act of terrorism but said the situation was unprecedented in New Zealand.
Several others are shown gathering in front of the scene that was surrounded with police tape.
As New Zealand tried to come to terms with shootings at two Christchurch mosques, which police said left 49 dead and dozens injured, witnesses recounted what they saw as a gunman opened fire on worshippers.
The Los Angeles Police Department posted to Twitter that while it had no indication that any related attacks would be carried out in the city, it would increase patrolling around L.A. mosques "out of an abundance of caution".
He's been charged with murder appeared in court.
Givealitte: This New Zealand-based crowdfunding platform is hosting a live campaign where people can donate for victim support.
Trudeau said Canada "remembers too well the sorrow" felt following an attack on a mosque in Quebec.
Investigators were said to be trying to establish whether or not the other two people arrested were involved in the attacks.
An anti-immigrant manifesto purportedly written by the man in police custody was posted on Twitter and the online forum 8chan shortly before the shootings. Additionally, New Zealand does not ban the ownership of semi-automatic military-style assault weapons, also in contrast to Australia.
"I can tell you one thing right now, our gun laws will change", Ardern told reporters.
Ardern, who was flying to Christchurch on Saturday, said she had spoken to Trump, who had asked how he could help.
Dozens of people laid flowers at cordons near both mosques in the South Island city, which is still rebuilding after a devastating quake in 2011 that killed nearly 200 people.
He said he planned to target a mosque in Dunedin, but switched to the Al Noor and Masjid Mosques as they had "far more invaders".
"But as we condemn the horrific terrorist act in New Zealand, we also must commit ourselves to fighting hatred wherever we find it", Nenshi said.
Australian Senator Faser Anning released a statement blaming "the immigration program which allowed Muslim fanatics to migrate to New Zealand in the first place" as "the real cause of bloodshed" following Friday's shootings.