New Zealand Prime Minister Jacinda Ardern said Thursday that the country will ban assault weapons and semi-automatic “military-style” guns, and there will be a gun buyback.

Ardern made the announcement less than a week after 50 people died in a mass shooting at mosques in Christchurch, New Zealand. In the wake of the shooting, the prime minister had vowed to announce changes to national gun laws within 10 days.

"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 Thursday.

"Related parts used to convert these guns into MSSAs are also being banned, along with all high-capacity magazines,” she added.

Ardern said she expected new legislation to be in place by April 11 and that there would be stop guards put in place to prevent a surge of gun sales before the government buyback. She said the buyback is expected to cost between $100 million and $200 million.

The shooting, which is the seventh deadliest gun massacre worldwide, was allegedly conducted by a white supremacist who livesteamed the attack. New Zealand last updated its gun laws more than 25 years ago.