It is horrific but what what makes is so much that way is that it happened in a very peaceful western democracy. Univ of Maryland's Global Terrorism Database, which the US Government supports and uses, lists over 167,000 terror related deaths between 2001 and 2015, with an additional thousands to date. 98% were in Muslim countries, killing other Muslims although Christian and other minorities are certainly among those.
So many Muslims who have emigrated fled their countries to get away from the mayhem and carnage (not all), such as probably NZs small Muslim population, and now it followed them. One of the saddest reports is the last words of one victim who said "Welcome brother" to the shooter just before he was murdered.
While I would not describe myself as a religious person, I would like to believe that those who died while at prayer, are now with God.