[Only registered and activated users can see links. ]Forty people have been killed and more than 20 seriously wounded in shootings at two mosques in Christchurch.
New Zealand's Prime Minister Jacinda Ardern described the incidents as a terrorist attack, and one of the country's "darkest days".
Three men and one woman are in custody, police commissioner Mike Bush said, but warned more suspects may be at large.
Australia's Prime Minister Scott Morrison said one of those arrested was an Australian citizen.
He described the suspected attacker as an "extremist right-wing violent terrorist".
He posted on 8Chan a while back saying he was going to do it and provided his Facebook account so he could stream it live from his GoPro on his head.
I've seen the video, grim as fuck. He goes back to his car for more bullets and then goes back in again.
What a fucked up world when these individuals exist.