“We believe that 40 people have lost their lives in this act of extreme violence,” she said.

“Ten have died at Linwood Avenue mosque. Three of which were outside the mosque itself.”

“A further 30 have been killed at Deans Avenue mosque.”

“What I can say is that it is clear that this is one of New Zealand’s darkest days,” she said.

Ardern said there was no place in her country for those who opened fire at two mosques, killing multiple people at prayer.

New Zealand Police Commissioner Mike Bush has said three men and a woman are in custody after the multiple fatalities at two mosques in Christchurch.

Australian man Brenton Tarrant is among those arrested.

“The attackers were apprehended by local police staff, there has been some absolute acts of bravery,” Bush said.

He said police were not aware of any other people being involved in the attacks, but cannot rule out the possibility.

The mosques and a number of schools are in lockdown and police were saturating the areas with staff.

Ardern said those attacked should have been safe.

Many of those who were killed or injured may be migrants to New Zealand, even refugees, she said.

“They have chosen to make New Zealand their home, and it is their home. They are us.

“The person who has perpetuated this violence against us is not. They have no place in New Zealand.”

Tarrant has issued a 74-page “manifesto” saying he carried out the fatal shootings at Christchurch mosques to avenge the deaths of thousands in Europe.

The man had prepared his manifesto titled “The Great Replacement” and posted it on a message board website.

He described himself as “Just an ordinary White man, 28 years old. Born in Australia to a working class, low income family.”

Under a heading “Why did you carry out the attack?”, he said it was to avenge “thousands of deaths caused by foreign invaders”.

Ardern said the killings occurred in a place where people were expressing their religious freedom.

“Where they should have been in a safe environment, and they have not been today,” she said.

Bush warned people not to go to any mosque, anywhere in New Zealand today.

“It is a very serious and grave situation,” he said.

It began when a gunman opened fire at a mosque at 1.40pm local time, with witness saying there may have been up to 500 people present.

Police are warning people to stay indoors.

Ardern said she knew staying inside meant some families were separated, but urged people to remain in lockdown until advised otherwise by police.

more to come

-AAP