New Zealand will ban military style semi-automatic and assault rifles under tough new gun laws following the killing of 50 people in the country's worst mass shooting, Prime Minister Jacinda Ardern said on Thursday. Ardern said she expects the new laws to be in place by April 11 and buy-back scheme will be established for banned weapons. "Now, six days after this attack, we are announcing a ban on all military style semi-automatics (MSSA) and assault rifles in New Zealand," Ardern said.