Jacinda Ardern, the New Zealand’s prime minister, condemned the act as a terrorist attack and called “an extraordinary and unprecedented act of violence,” interrupted a day of prayer for a small immigrant community in the nation’s third-largest city and shook a country with little history of mass shooting.
Harrowing first-person footage, apparently from a camera worn by a gunman as he attacked the Al Noor Mosque in the center of the city, was streamed on Facebook, a grim development in terrorism that raised questions about the ability of global tech companies to block violent content from spreading around the world.
Facebook said it quickly shut down the account, but a 17-minute video showing a man dressed in black shooting at fleeing worshipers and into piles of bodies with a semiautomatic rifle circulated widely online. In addition to those killed, at least 20 were injured, the authorities said.
The police said a man in his late 20s was arrested and charged with murder but declined to identify him. The police also said they seized several weapons and found two explosive devices on a vehicle.
Schools in the downtown area were locked down for hours after the attacks as the police tried to determine whether the gunman acted alone. The authorities urged residents to stay indoors, asked mosques to close and cleared nearby Cathedral Square, where people had gathered as part of worldwide protests to demand action on climate change.
New Zealand’s police commissioner, Mike Bush, said three other individuals found near the scene with weapons were also taken into custody, though investigators later said that one probably had nothing to do with the attacks.
The shootings were first reported at about 1:40 p.m., around the time of the midday Friday prayer, when the Al Noor Mosque and the Linwood Mosque, about three miles east, would be most busy. Minutes earlier, Mr. Bush said, the manifesto appeared online.
The document named both mosques, and links to it were posted on Twitter and 8chan, an online forum known for hosting message boards with extremist right-wing discussions. The 8chan post included a link to what appeared to be the gunman’s Facebook page, where he said he would soon broadcast live video of the attack.
Ms. Ardern said that many of the victims were most likely migrants to New Zealand or refugees.
She added that New Zealand was likely targeted “because we represent diversity, kindness, compassion, a home for those who share our values, refuge for those who need it.”
Nasreen Hanif, a spokeswoman for the Islamic Women’s Council of New Zealand, said people were anxious for updates and were worried that friends or family members were among the dead.
“Nobody’s answering their phones,” she said. “We don’t know if they’re at the hospital or out of reach. Some have posted that they are safe, but others have not.”
Ms. Hanif said the two mosques in Christchurch had asked for help from Muslims across the country to arrange the 49 funerals they would need to plan.
Bangladesh team escaped from a mosque near Hagley Park where there were active shooters. They ran back through Hagley Park back to the Oval. pic.twitter.com/VtkqSrljjV
— Mohammad Isam (@Isam84) March 15, 2019