CHRISTCHURCH, New Zealand (AP) — At least 49 people were shot to death at two mosques during midday prayers Friday — most if not all of them gunned down by an immigrant-hating white supremacist who apparently used a helmet-mounted camera to broadcast live video of the slaughter on Facebook.

One man was arrested and charged with murder. Brenton Harrison Tarrant appeared in court Saturday morning amid strict security and showed no emotion when the judge read him one murder charge. The judge said “it was reasonable to assume” more such charges would follow.

Two other armed suspects were taken into custody while police tried to determine what role, if any, they played in the cold-blooded attack that stunned New Zealand, a country so peaceful that police officers rarely carry guns.

It was by far the deadliest shooting in modern New Zealand history.

“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.”

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.

The gunman also livestreamed in graphic detail 17 minutes of his rampage at Al Noor Mosque, where, armed with at least two assault rifles and a shotgun, he sprayed worshippers with bullets over and over, killing at least 41 people. Several more people were killed in an attack on a second mosque in the city a short time later.

At least 48 people were wounded, some critically. Police also defused explosive devices in a car.

Police did not say whether the same person was responsible for both shootings. They gave no details about those taken into custody except to say that none had been on any watch list.

Tarrant’s relatives in the Australian town of Grafton, in New South Wales, contacted police after learning of the shooting and were helping with the investigation, local authorities said. Tarrant has spent little time in Australia in the past four years and only had minor traffic infractions on his record.

On Saturday, outside one of the two mosques, 32-year-old Ash Mohammed pushed through police barricades in hopes of finding out what happened to his father and two brothers, whose cellphones rang unanswered. An officer stopped him.

“We just want to know if they are dead or alive,” Mohammed told the officer.

In the aftermath, the country’s threat level was raised from low to high, police warned Muslims against going to a mosque anywhere in New Zealand, and the national airline canceled several flights in and out of Christchurch, a city of nearly 400,000.