New Zealand is banning all assault rifles, high-capacity magazines and military-style semi-automatic rifles in response to the nation's deadliest massacre in history, the country's prime minister announced Thursday.

Jacinda Ardern said the ban goes into effect immediately and would be followed by legislation next month. New Zealand's citizens should make arrangements to turn in weapons banned under the new laws, Ardern told the nation in a live television announcement.

"On March 15, the nation witnessed a terrorist attack that demonstrated the weakness of New Zealand's gun laws," Ardern said. "The guns used in this attack had the power to shoot continuously. The times for the easy availability of these weapons must end. And today, they will."

She added, "We just want the guns back. ... It's about all of us. It's in the national interest, and it's about safety."

Ardern says the alleged shooter in Friday's attacks at two Christchurch mosques killed most of the 50 people with two legally purchased semi-automatic rifles modified with 30-plus round magazines, "essentially turning them into military-style semi-automatic weapons."

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She said an amnesty will be put in place for weapons to be handed in by citizens. The New Zealand cabinet will also implement a buyback plan for banned weapons, and there will be "tightly regulated" exemptions for some owners such as hunters and farmers.

"I strongly believe that the vast majority of legitimate gun owners in New Zealand will understand that these moves are in the national interest, and will take these changes in their stride," she said. She also noted that gun ownership is "a privilege and not a right" in New Zealand.

Her words were already being put into effect across the nation: The New Zealand government immediately began asking all owners of assault weapons or now-banned attachments to report them to the government in the next two days before turning them in.

Since the attacks, Ardern has led a nation trying to grieve and work through the news of the killings, which, in total, rival the annual number of murders in New Zealand.

On Tuesday, Ardern had told New Zealand's Parliament that tough gun laws were coming. She also said she would deny the man responsible for the nation's worst terror attack in modern history the one thing he likely craved: fame.

"He is a terrorist, he is a criminal, he is an extremist, but he will, when I speak, be nameless, and to others I implore you: Speak the names of those who were lost rather than the name of the man who took them. He may have sought notoriety but we in New Zealand will give him nothing – not even his name."

Ardern opened her speech to lawmakers in New Zealand by using the Arabic greeting "As-salamu alaykum." In English, this translates as "Peace be upon you."

"You may have chosen us," Ardern said, the anger rising in her voice as she condemned the suspect in the attacks. "But we utterly reject and condemn you."

New Zealand has fewer restrictions on rifles or shotguns than many countries. Handguns are more tightly controlled.

About 1.5 million firearms are owned – legally and illegally – by civilians in New Zealand, according to police data tracked by GunPolicy.org, a website run in conjunction with the University of Sydney. This equates to about 30 firearms per 100 people. In the United States, the rate is approximately 120 firearms per 100 people, according to the site.

All gun owners in New Zealand must have a license, which they can get from age 16 (age 18 for semiautomatic weapons) but the weapon itself does not need to be registered with authorities, according to the Council of Licensed Firearms Owners, a New Zealand lobby group. Ardern said the suspect in Friday's attacks had a license and owned five guns. The majority of firearms owners in New Zealand are farmers or hunters.

According to GunPolicy.org, New Zealand is among a handful of countries where police officers are routinely unarmed when they are on patrol. Officers in Britain, Ireland, Norway and Iceland also carry firearms only in special circumstances.

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Australia and Britain both changed their gun laws in response to mass shootings.

The Australian government overhauled its guns laws in 1996 after 35 people were murdered during a shooting spree in Tasmania. Australia banned all semi-automatic weapons and restricted certain handguns. It offered to buy back prohibited firearms.

A 2016 study published in the Journal of the American Medical Association found that Australia hadn't had a fatal mass shooting – one in which five or more people are killed – since the 1996 shooting. In the 18 years prior to the new laws, there were 13.

The turning point for Britain came in 1996, when a man used a legally owned handgun to kill 16 young children and a teacher at a school in Dunblane, Scotland. In the aftermath, all private ownership of handguns was banned.

Since then, there has been one mass shooting, in 2010, in Britain.

The death toll in the attack at the Al Noor and Linwood mosques rose to 50 people Saturday; victims range in age from 2 to over 60.

Services for the victims were held at churches across the country Sunday, and people laid flowers at memorial sites. A group of bikers performed the haka – a traditional ceremonial dance of New Zealand's Maori people – at the memorial in Christchurch.

Thirty-nine people remain in the hospital, and 11 were in intensive care in critical condition.

Contributing: Kim Hjelmgaard, USA TODAY; Associated Press