Mike Bush the Police Commissioner said that it is possible that there are more people involved in the2 coordinated terrorist attacks.
A total of four people - three men and one woman - are now in custody and will appear in court tomorrow. One of the shooters had livestreamed the attack online and had said, "Remember lads, subscribe to PewDiePie". "Everybody just ran to the back doors to save themselves", one eye witness said.
In 2010 and 2011 the city suffered a series of devastating earthquakes, with the most destructive at 6.3 magnitude, which killed almost 200 people and destroyed thousands of buildings.
Muslims account for just over 1 percent of New Zealand's population, a 2013 census showed.
Tarrant, who police say carried out at least one of the shootings, posted a jumbled, 74-page manifesto on social media in which he identified himself by name and said he was a 28-year-old Australian and white supremacist who was out to avenge attacks in Europe perpetrated by Muslims.
Before Friday, New Zealand's worst mass shooting was in 1990 when a gun-mad loner killed 13 men, women and children in a 24-hour rampage in the tiny seaside village of Aramoana.
"This is one of New Zealand's darkest days", Adern said. Gray also said she recalled that Tarrant's father Rodney died from some kind of asbestos-related illness when Tarrant was finishing high school.
She added: "Today, at mosques across Scotland and elsewhere, Muslims will attend Friday prayers. At that moment, I realised it was really serious", the man said.
Australian prime minister Scott Morrison said one of the suspects in the "rightwing extremist attack" was an Australian-born citizen.
New Zealand's Prime Minister Jacinda Ardern called the incident a terrorist attack in a Friday press conference, saying the suspects held "extremist views" that have no place in New Zealand or the world.
The two mosques are about five kilometres apart.
The man who claimed responsibility for the shooting said he came to New Zealand only to plan and train for the attack.
He said he chose New Zealand because of its location, to show that even the most remote parts of the world were not free of "mass immigration".
Last year, New Zealand's prime minister announced that the country would boost its annual refugee quota from 1,000 to 1,500 in 2020.
The visiting Bangladesh cricket team was arriving for prayers at one of the mosques when the shooting started but all members were safe, a team coach told Reuters.
Home to almost 400,000 people, Christchurch is the largest city on New Zealand's South Island.
Christchurch, sometimes called the Garden City, has been rebuilding since an natural disaster in 2011 killed 185 people and destroyed many downtown buildings.