Forty-nine people have been killed and at least 20 wounded in shootings at two mosques in Christchurch, New Zealand, in the nation’s deadliest attack.

Prime Minister Jacinda Ardern described it as a terrorist attack and one of New Zealand’s “darkest days”.

A gunman identifying himself as an Australian live-streamed the rampage at Al Noor mosque to Facebook. He had espoused racist, anti-immigrant views.

Police say a man in his late 20s has been arrested and charged with murder.

Two other men and one woman were also detained. One was released later.

No names have been made public. Firearms and explosive devices were recovered, Police Commissioner Mike Bush said.

The gunman live-streaming the attack from a head-mounted camera said he was a 28-year-old Australian called Brenton Tarrant. The footage showed him firing indiscriminately at men, women and children from close range inside the Al Noor mosque.

Police called on the public not to share the “extremely distressing” footage online. Facebook said it had removed the gunman’s Facebook and Instagram accounts and was working to remove any copies of the footage.

The suspect who was charged appeared to have published a document before the attack outlining his intentions as well as details about the plan for the attack. He is due in court on Saturday morning.

Australian Prime Minister Scott Morrison described the man as an “extremist, right-wing” terrorist. New Zealand Police Commissioner Bush confirmed that the man was not known in advance to either New Zealand or Australian security services.