The Muslim community is on high alert, with worshippers told to stay away from all mosques nationwide.
There are more than 70 Islamic centres across the country, and around 50,000 New Zealanders who identify as Muslim.
Places of worship are now under armed guard, specialist police seen protecting Kilbirnie Mosque in Wellington.
Islamic leader Hazim Arafeh is in shock.
"I'm absolutely gutted, I'm shattered," he told Newshub.
"I don't think there's anything worse in the whole of New Zealand history and what adds to our pain is that there's another attacker that's also attacked another masjid (mosque)."
Armed police have been outside the Palmerston North mosque too. Among those offering their support were Immigration Minister and local MP Iain Lees Galloway, and an Anglican Minister Andy Hickman, who came to talk to his Muslim counterpart.
"We're all on the same time, we're all here as team human, so their loss and their grief is ours, and so we just pray for their peace and pray for their wellbeing," Mr Hickman said.
Prominent Muslim Sonny Bill Williams was among those struggling to contain his grief.
"Just heard the news and I couldn't put it into words how I'm feeling right now."