CHRISTCHURCH, New Zealand — Huzef Vohra is haunted by flashbacks.

The roar of a motorcycle, a loud bang, a whistle-like snore — they catapult the civil engineer back to March 15, to the bottom of a pile of bodies in the corner of Al Noor Mosque. In the disoriented rush that followed a gunman opening fire there, Vohra, 21, charged toward an exit but was quickly caught in the stampede to escape.

“People toppled on top of me,” he said. “I was trapped.”

As Vohra lay there for what seemed like forever, he felt a series of thumps — each one a gunshot into the mass of bodies above him.

Six months later, Vohra and many others in this county of nearly 5 million are still grappling with a pair of attacks on two Christchurch mosques, Al Noor and the Linwood Islamic Center. Authorities have described the massacre as an act of terror carried out by a suspected white supremacist, who will face trial next year. With a death toll of 51, March 15 marks the worst atrocity in New Zealand’s modern history.

Flowers and messages of support at the Al Noor mosque. Hagen Hopkins / for NBC News

As relatives mourn the dead and survivors adjust to life after the attack, New Zealand’s leaders have responded with a slate of sweeping policy changes. A mandatory gun buyback has netted more than 19,000 semi-automatic weapons, while Prime Minister Jacinda Ardern’s effort to eliminate violent extremism online has been embraced by a handful of big tech companies, as well as more than a dozen countries including the United Kingdom, India and Australia. On Friday, a bill was introduced that would track all the guns in the country through a new register.

These moves have been met with widespread but not universal support. A push for tougher hate speech laws reportedly prompted its own hate-fueled backlash against an Iranian-born member of Parliament, Golriz Ghahraman.

There’s been introspection, too. Commentators and academics questioned New Zealand’s peaceful, progressive reputation, pointing to its colonial past and the persistence of far-right extremism. A television journalist apologized to viewers for never covering white supremacy.

“Maybe these events held a mirror up to New Zealand, and we didn’t much like the reflection,” said Peter Thompson, a senior lecturer in media studies at Victoria University of Wellington. “We weren’t as tolerant a society as we cared to think.”

Still, there were large and small acts of solidarity. Days after the shooting, the Muslim call to prayer was broadcast nationally. Ardern has worn a hijab to public events, most recently to the national conference of the Islamic Women’s Council last month.

Prime Minister Jacinda Ardern hugs a mourner at the Kilbirnie Mosque on March 17, 2019, in Wellington, New Zealand. Hagen Hopkins / Getty Images file

At Al Noor, a small suburban mosque just outside central Christchurch, congregants said that such acts offered a measure of assurance.

Usman Afzali, 34, a graduate student at the University of Canterbury, recalled consoling a friend whose father and brother were among the more than 40 worshippers killed at Al Noor. It was March 16, and hundreds of Muslims had gathered at a local college seeking information about their missing relatives, he said. Neither Afzali nor his friend knew that Ardern would be there, too, wearing a headscarf and comforting grieving families.

“We thought, ‘This is different now, because it is not only on us,’” he said. “It is on all of New Zealand.”