One gunman is believed to be responsible for both Christchurch mosque shootings in which 49 people died, Police Commissioner Mike Bush says.
Brenton Tarrant, 28, appeared in Christchurch District Court on Saturday morning charged with murder.
Two others remain in custody. Police are yet to determine if they had any connection to the terror attacks.
The first attack was at the Al Noor Mosque in Deans Ave, central Christchurch, where scores of people were gunned down while attending Friday prayers. Forty-one people shot there have died so far.
The second attack was at Linwood Ave mosque, where a further seven people were shot and killed, and others injured.
One more person died in Christchurch Hospital, bringing the death toll to 49.
It took the shooter seven minutes to drive to the second mosque.
ARREST MADE IN 36 MINUTES
Police made an arrest on Brougham St 36 minutes after they were first called to the central city mosque.
Bush said he was in Wellington, listening to a live stream of officers at the time of the arrest.
He said the person in the car "was not willing to be arrested" and he credited the arresting officers for their act of bravery.
The car, a gold Subaru, had two bombs (improvised explosive devices) and firearms in it. A cordon was set up and a bomb disposal unit disabled the devices.
A fourth person was arrested outside Papanui High School, because they had a gun with them while picking up a child. That person was later released.
'OUR LAWS WILL CHANGE'
On Saturday, Prime Minister Jacinda Ardern said gun laws would change in light of Friday's shootings.
She said the main offender was in possession of a gun licence, obtained last November. Five guns were used in the attack including two semi-automatic weapons.
Ardern said more work will be done to trace the guns but made one thing clear: "Our gun laws will change."
Ardern said Friday was one of New Zealand's "darkest days."
"It is clear that this can now only be described as a terrorist attack," Ardern said.
It appeared to have been "well-planned."
"This was an act of extraordinary and unprecedented violence. It has no place in New Zealand."
"Many of the people affected by this act of extreme violence will be from our refugee and migrant communities. New Zealand is their home. They are us.
"The person or people who carried out this act of unprecedented violence are not. There is no place in our home for them."
Bush urged New Zealanders to stay safe, and asked Christchurch residents to stay inside and said all mosques around the country should shut their doors until further notice.
"We urge New Zealanders to stay vigilant and report any suspicious behaviour immediately to 111."
A heavy police presence will continue in Christchurch and there will be heightened police presence at community events for safety and reassurance. "Dozens of officers continue to be deployed into the region today, and Police's Eagle helicopter has flown to Christchurch to assist those on the ground." Police and the wider government will be working with leaders and members of the Islamic community to provide assistance, reassurance and support.
The gunman livestreamed the shooting online and police are reminding the public it is an offence to distribute an objectionable publication and anyone who does could face prison.
FEARS FOR THE MISSING
Family members are appealing for sightings of their missing loved ones, including several children.
Red Cross has started a missing persons list.
Canterbury District Health Board chief executive David Meates said they were still treating 36 people in Christchurch Hospital and about 200 family members were there waiting news of their family members.
Members of the public can register missing persons or register themselves as alive on the Restoring Family Links (RFL) website. People living in New Zealand can also register missing persons by calling 0800 115 019.
VIGILS TO BE HELD
Vigils and memorial services will be held across the country.
Hamilton: Hamilton's love to Christchurch vigil in Claudelands Park starts at 8pm on Saturday.
Christchurch: A memorial event will be held at Cathedral Square on Thursday at 8.30pm.
Dunedin: Amnesty Otago will host a vigil at the Octagon on Thursday at 7pm.
Invercargill: A vigil for peace and solidarity will take place at Wachner Place at 11am on Sunday.
Across the country: Several churches are also opening their doors to the public during the weekend.
Haven Falls funeral homes have opened their chapels in Whangarei, Auckland and Wellington for a service at 7pm on Saturday and are open at any time for the Muslim communities to use for service.
Police said in a statement they wanted vigil organisers to let them know about events.