- A male in his late 20s has been charged with murder and is due to appear at a Christchurch court on Saturday morning.
Brenton Tarrant, 28, from Australia, was named in media reports in his home country as the gunman who appeared to have live-streamed the attack.
In a 74-page manifesto, believed to have been written by Tarrant, he describes anti-immigrant motives, saying the victims were a "large group of invaders" who he says "seek to occupy my peoples lands and ethnically replace my own people (sic)".
Two other people were being held in custody and police said they were trying to determine how they might be involved.
New Zealand prime minister Jacinda Ardern confirmed that a total of 49 people have been killed and at least 20 others had been seriously injured.More news: What went right, what went wrong in Dubs' win vs. Rockets
Bush clarified that police had found two improvised explosive devices in one auto.
He added: " Out of respect and in condolence for all those killed in the terrorist attack in New Zealand, I have asked for flags to be flown at half-mast".
She said the focus of New Zealand's security agencies have been monitoring extremism "regardless of where it comes from".
Mark Nichols told the New Zealand Herald he heard about five gunshots and that a Friday prayer-goer returned fire with a rifle or shotgun.
He describes himself as "a private and mostly introverted person" and admits he is racist, adding that he is an "Eco-fascist by nature". The gunman spends more than two minutes inside the mosque spraying terrified worshippers with bullets again and again, sometimes re-firing at people he has already cut down. "I saw lots of broken glass and bricks on the backside of the mosque", he said.
Australian Prime Minister Scott Morrison said one of the men in custody was Australian.More news: Man blocks arrow fired at him with mobile phone
He said he was inspired by Norwegian shooter Anders Breivik.
"I came to the street I saw one person got shot on his chest", he said, adding that the ambulance and police then arrived on the scene.
Tarrant, and another gunman targeted two mosques during the bloodbath, injuring at least twenty people.
Shocked and strongly condemn the Christchurch, New Zealand, terrorist attack on mosques.
"If your child was attending the climate change protest in Cathedral Square and you want to check if they are in the Civic Offices, please call the Council Contact Centre on 03-941-8999", Christchurch City Council said.
Just 1% of New Zealand's population of nearly five million are Muslim, according to government statistics, less than 50,000 people in 2013.More news: UEFA to investigate Neymar's VAR criticism after PSG defeat
Home to almost 400,000 people, Christchurch is the largest city on New Zealand's South Island. This is a place where people should feel secure and will feel secure.