At least 49 people have been killed in mass shootings at two mosques full of worshippers attending Friday prayers in an attack broadcast in horrifying live video by an immigrant-hating white nationalist wielding at least two rifles.

One man was arrested and charged with murder, and two other armed suspects were taken into custody while police tried to determine what role they played.

“It is clear that this can now only be described as a terrorist attack,” prime minister Jacinda Ardern said, noting that many of the victims could be migrants or refugees.

She pronounced it “one of New Zealand’s darkest days”.

The attack shocked people across a nation of five million people which has relatively loose gun laws but is so peaceful even police officers rarely carry firearms.

The gunman behind at least one of the mosque shootings left a 74-page manifesto that he posted on social media under the name Brenton Tarrant, identifying himself as a 28-year-old Australian and white nationalist who was out to avenge attacks in Europe by Muslims.

Using what may have been a helmet camera, he live-streamed to the world in graphic detail his assault on worshippers at Christchurch’s Al Noor Mosque, where at least 41 people were killed.

An attack on a second mosque in the city not long after killed several more.

POLICE New Zealand
(PA Graphics)

Police did not identify those taken into custody and gave no details except to say that none of them had been on any watch list.

At least 48 people, some in critical condition, were being treated at Christchurch Hospital for gunshot wounds, authorities said.

While there was no reason to believe there were any more suspects, the prime minister said the national threat level was raised from low to high.

Police warned Muslims against going to a mosque anywhere in the country, and Air New Zealand cancelled several flights in and out of Christchurch, saying it could not properly screen customers and baggage.

Police said the investigation extended 240 miles to the south, where homes in Dunedin were evacuated around a “location of interest”.

Witness Len Peneha said he saw a man dressed in black enter the Al Noor mosque and then heard dozens of shots, followed by people running out in terror.

Mr Peneha, who lives next door, said the gunman ran out of the mosque, dropped what appeared to be a semi-automatic weapon in his driveway and fled. He said he then went into the mosque to try to help the victims.

“I saw dead people everywhere. There were three in the hallway, at the door leading into the mosque, and people inside the mosque,” he said. “I don’t understand how anyone could do this to these people, to anyone. It’s ridiculous.”

He said the gunman was wearing a helmet with some kind of device on top, giving him a military-type appearance.

Police at the mosque in Linwood
Police at the mosque in Linwood (Mark Baker/AP)

In the video that was apparently live-streamed, the gunman spends more than two minutes inside the mosque spraying terrified worshippers with bullets again and again, sometimes firing at people he has already cut down.

He then walks outside, where he shoots at people on the pavement. Children’s screams can be heard in the distance as he returns to his car to get another rifle. The gunman then walks back into the mosque, where there are at least two dozen people lying on the ground.

After going back outside and shooting a woman there, he gets back in his car.

The second attack took place at the Linwood mosque about three miles away.

The man who claimed the Al Noor shooting said he was not a member of any organisation, acted alone and chose New Zealand to show that even the most remote parts of the world are not free of “mass immigration”.