Why was the country, thought of as among the most peaceful in the world, singled out for a horrifying terrorist attack?

This South Pacific nation, hailed by Muslim immigrants as a "heaven on earth", ranks second only to Iceland on the Global Peace Index.

But in just 36 minutes on Friday afternoon, 49 Muslims were shot dead at two Christchurch mosques, leaving more dead than there were murders in all of last year.

In a country where police routinely patrol unarmed, parents strained to explain to their kids what happened, even as they struggled to understand it themselves.

A sole gunman "made the point that there is nowhere that's far enough away", said Chris, who took his children aged 12, nine and four, to the scene of the Linwood mosque where seven were gunned down.

"It's a fine line between telling the children this is the reality of it," he said, "and not exposing them to the true nature of humanity that can lead to this sort of thing."

Nearby, a heavily armed policewoman tried to explain to two young girls she was holding a rifle to keep them safe, to which one of the girls responded by saying the gunman had used a rifle to kill people.

Paradise lost?

New Zealand is not a Utopia, there are occasional reports of racism and anti-immigrant attitudes, but they attract headlines because they are not the norm.

"I live in New Zealand because the first time I came here in 2011, I found a place that was heaven on earth and I decided to bring my family to live here in peace, away from all the troubles," a Palestinian man told AFP.

People from all walks of life arrived at the police barriers near the mosques on Saturday to pay their respects and to show support for New Zealand's 50,000 Muslims, who make up about one percent of the population.

"This is not something you'd expect on our soil," said Luke Smith, who was also in Christchurch eight years ago when devastating earthquakes killed 185 people.

"It's a different sort of feeling to the earthquakes. That being a natural disaster and this being an outright act of terrorism. It leaves you feeling totally different.

"Shock would be the biggest way to describe it. You don't think it's going to happen on our soil."

Chris said it showed New Zealand's geographical isolation counted for little in a connected world.

"It shows you can immerse yourself in a nice, gentle society and in the social media part, he can immerse himself in another community that reinforces his ideas and rage."

On the sombre streets of Christchurch, Jeremy Mitchell said it was "surreal" such a massacre could happen in New Zealand.

"I think everyone in the community is 100 percent in support of the Muslim community and the Muslim families who have lost their loved ones.

"We want to say we have no part of that (massacre) and we don't believe what (the gunman) believes."