Prime Minister Jacinda Ardern and thousands of others congregated in leafy Hagley Park opposite the Al Noor mosque in Christchurch to observe the call to prayer at 1:30 p.m.

"New Zealand mourns with you. We are one," Ardern said.

Thousands more listened on the radio or watched on live television. The prayer was followed by two minutes of silence.

On a light brown carpet, hundreds of Muslim men sat in socks or bare feet readying for the prayer. One man in the front row was in a Christchurch Hospital wheelchair.

The Al Noor mosque's imam, Gamal Fouda, thanked New Zealanders for their support.

"This terrorist sought to tear our nation apart with an evil ideology. ... But, instead, we have shown that New Zealand is unbreakable," the imam said.

"We are broken-hearted but we are not broken. We are alive. We are together. We are determined to not let anyone divide us," he added, as the crowd erupted with applause.

Fahim Imam, 33, returned to his hometown for the service. He left Christchurch three years ago and now lives in Auckland, New Zealand's largest city.

"It's just amazing to see how the country and the community have come together — blows my mind, actually," Imam said before the event.

When he got off the plane Friday morning, he saw someone holding a sign that said "jenaza," denoting Muslim funeral prayer. He said others were offering free rides to and from the prayer service.

"The moment I landed in Christchurch, I could feel the love here. I've never felt more proud to be a Muslim, or a Kiwi for that matter. It makes me really happy to be able to say that I'm a New Zealander," Imam said.

He called it surreal to see the mosque where he used to pray surrounded by flowers.

The observance comes the day after the government announced a ban on "military-style" semi-automatic firearms and high-capacity magazines like the weapons that were used in last Friday's attacks.

Forty-two people died at the Al Noor mosque and seven at the nearby Linwood mosque. One person shot at one of the mosques died later at a hospital.

An immediate sales ban went into effect Thursday to prevent stockpiling, and new laws would be rushed through Parliament that would impose a complete ban on the weapons, Ardern said.

"Every semi-automatic weapon used in the terrorist attack on Friday will be banned," Ardern said.

The gun legislation is supported not only by Ardern's liberal Labour Party but also the conservative opposition National Party, so it's expected to pass into law. New Zealand does not have a constitutional right to bear arms.

Among those planning to attend Friday's observance was Samier Dandan, the president of the Lebanese Muslim Association in Sydney and part of a 15-strong delegation of Muslim leaders that had flown to Christchurch.

"It was an ugly act of terrorism that occurred in a beautiful, peaceful city," Dandan said.

He said his pain couldn't compare with that of the families he'd been visiting who had lost loves ones. He was inspired by their resilience, he said.

"And I've got to give all my respect to the New Zealand prime minister, with her position and her actions, and it speaks loud," he said.

Ismat Fatimah, 46, said it was sad to look at the Al Noor mosque, which was still surrounded by construction barricades, armed police officers and a huge mound of flowers and messages.

"We're feeling stronger than before, and we are one," she said.

She said she prayed for the people who died.

"I'm just imagining what would be happening last Friday," she said. "People were running around so scared and helpless. It's just not right."

Erum Hafeez, 18 said she felt comforted by the overwhelming response from New Zealanders: "We are embraced by the community of New Zealand, we are not left behind and alone."

The Al Noor mosque's imam said workers have been toiling feverishly to repair the destruction, some of whom offered their services for free. Fouda expects the mosque to reopen by next week.