The article above stated four people were arrested and there may be more involved. The author noted several alt right groups in New Zealand that may be providing support. Via social media this Aussie nut job is now a new celebrity.

https://www.abc.net.au/triplej/progr...nline/10907056

Fuelled by a toxic, alt-right echo chamber, Christchurch shooter's views were celebrated online

One of the men suspected of carrying out a mass shooting in Christchurch published a manifesto that's now being circulated on alt-right forums, where his actions are being celebrated as part of a broader race war.
One of the gunmen, who identified himself as a 28-year-old Australian named Brenton Tarrant, livestreamed on Facebook the shooting at the Al Noor Mosque.
The manifesto begins with the Dylan Thomas poem 'Do not go gentle into that good night / Rage, rage against the dying of the light', and then describes a situation where 'European countries' including Australia and New Zealand are growing weaker because of their lower birth rates.
I can understand the anger that the recent mass and unmitigated migration generates. It is an asymmetric threat, but no less dangerous than a kinetic war to the existence of one's existing culture. To be clear, the alt-right and their narrative of hate alone are guilty of this atrocity. However, far left politicians who promote policies that threaten their own societies need to step back and reflect on the divisions their policies of so-called inclusion are generating. You can see signs of mounting anger in Europe, the U.S., and completely by surprise, at to me, in New Zealand and Australia. We have policies that are generating internal instability that may turn out to be a greater threat than any external actor.