40 people have been killed and as many as 20 have been wounded in two attacks on two mosques in the center of Christchurch.

The attacks began just before 2pm on Friday afternoon. Three men and one woman have been arrested in relation to the violence. One of the attacks may have been livestreamed on social media, but apps like Twitter and Facebook are working to locate the video and have it removed immediately from the sites.

Little is known about the attackers at this point, but at least one has been confirmed as an Australian citizen. New Zealand Prime Minister Jacinda Ardern has said the attackers were not on watch lists.

An 87 page manifesto spouting anti-Muslim and anti-immigrant rhetoric justifying violence towards these communities was posted on social media shortly before the attacks began, though news outlets have been unable to confirm if that document is directly linked to the attackers.

Ardern has called the tragedies a terrorist attack and warned that the “extremist views” held by the terrorists will not be tolerated in New Zealand. Ardern went on to call the attacks “one of New Zealand’s darkest days.”

“For now my thoughts and I’m sure the thoughts of all New Zealanders are with those who have been affected their families,” she said.