Many New Zealand gun owners have voluntarily surrendered their semi-automatic rifles to police following Friday's terror attack at two mosques in Christchurch, Newsweek reported. Some have taken to social media to encourage others to follow their move. "Until today, I was one of the New Zealanders who owned a semi-automatic rifle," farmer John Hart tweeted. "On the farm they are a useful tool in some circumstances, but my convenience doesn't outweigh the risk of misuse. "We don't need these in our country. We have [to] make sure it's #NeverAgain."