Tarrant was arrested in a auto, which police said was carrying improvised explosive devices, 36 minutes after they were first called.
Tarrant, described by Australia's Prime Minister Scott Morrison as an "extremist, right-wing, violent terrorist", expressed admiration for other violent white nationalists and his intention to "create an atmosphere of fear" and to "incite violence" against Muslims.
Residents pay their respects by placing flowers for the victims of the mosques attacks in Christchurch.
Another victim, Haji Daoud Nabi, died trying to save a fellow worshiper, his son told an Australian newspaper.
"This attack has been an enormous shock for all New Zealanders, and I am aware that there is a real sense of fear and concern for personal safety, particularly among our Muslim communities", New Zealand police commissioner Mike Bush said.
He has so far been charged with one count of murder, although judge Paul Kellar said it's "reasonable to assume" that more charges will follow, after yesterday's deadly shooting.
"But that arrest was tangential to this matter and we do not believe that he was involved in this attack either", he said.
The victims of Friday's shooting included immigrants from Jordan, Saudi Arabia, Turkey, Indonesia, and Malaysia.
Mosque worker Abdul Aziz risked his own life to challenge the gunman and try to snatch his weapon, according to attack survivor Syed Mazharuddin.
"The magnitude of this is the thing that is the most significant issue for people".
Hammond offers more spending, lower taxes if a Brexit deal is done
Last night's vote leaves a cloud of uncertainty hanging over our economy. "That is not what the British people voted for in June 2016", he said.
Bomb cyclone' fizzles to rain across US Midwest
Air rushed into the low-pressure area and then rose into the atmosphere, causing severe weather. A wind gust of 92 miles per hour (148 kph) was recorded in the mountains northwest of Denver.
Soil offered to Ethiopia crash families
Boeing has $7.6 billion in cash, but new revenue could face a hit because the company suspended deliveries of the Max on Thursday. It is too early to know whether the software or something else tilted the stabilizers up on the doomed Ethiopian plane.
Syrian refugee Khaled Mustafa, who had arrived in New Zealand with his family just months ago, was amongst those killed on Friday.
She also signalled that if convicted, he would serve his sentence in New Zealand.
Unlike the USA, the right to own a firearm is not enshrined in New Zealand's constitution.
The grandmother of the man allegedly responsible for the twin Christchurch mosque terror attacks that have killed 50 has spoken to 9News of her disbelief and devastation.
"I'm advised that there were five guns used by the primary perpetrator..."
According to a recent report from the Anti-Defamation League (ADL), domestic extremists killed 50 people in the United States past year - an overwhelming majority of which were perpetrated by right-wing extremists.
Ardern said she had spoken with Trump, who asked how he could help.
This senseless attack is an affront to the people of Christchurch and New Zealand, and the broader Muslim community.
During the emotional service the woman all held a placard with the words: "Peace will save the world #Solidarity with New Zealand mosque victims". "New Zealand is home for all of us, and this despicable act will not change that feeling of closeness in us".