Newshub has been told gun enthusiasts are buying up large before any proposed Government ban on semi-automatics may come into effect.
Gun City claims it's the world's largest gun shop. Newshub tried calling owner David Tipple, but his wife says he's been advised not to speak to media until he's spoken with police.
Tipple plans to hold a press conference tomorrow, during which he may address whether any of the weapons used to kill 50 people in Christhurch on Friday were bought at Gun City.
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On Saturday, Newshub obtained a photo of what appeared to be a near-new box for a Ruger AR556 - a semi-automatic - that had been dumped near the Deans Ave mosque.
On Sunday, they were on sale on the Gun City website at a discounted price.
University of Otago researcher Hera Cook has called for all sales and imports of semi-automatics to be stopped immediately until the Government decides what it will change.
"What's happened in the USA in situations like this has been that people rush out to buy more guns because they think they might get taken off the market."
New Zealanders are reporting a spike in gun sales too. Mike Loder, who runs a Kiwi pro-gun blog, posted to Facebook asking fellow enthusiasts how their sales were.
"Jacinda may be salesman of the year," he wrote.
Steve Burley, a gun shop owner from Paraparaumu, said he was flat out selling semi-autos, magazines and ammo.
When Newshub approached Burley he said he was too flat out selling guns to talk.
Loder is vehemently opposed to a semi-automatics ban. He says the Government has had a knee jerk response.
"What I'd like to see happen is that we wait first of all for the bodies to go in the ground, that would be dignified, and then we actually have something called an inquiry where we look into what actually happened."
But Philip Alpers, who's studied gun laws, says New Zealand has some of the most lax laws in the world - along with the US and Canada.
"The shooter could not have got his hands on these weapons in Australia," he told Newshub.
"One has to ask, did he go to New Zealand because New Zealand had the loopholes that allowed him to get those firearms?"
The Government is moving at incredible pace to get gun laws tightened. Policy was being drafted on Sunday to put in front of Cabinet the following day at their first meeting since the attack.
"[Gun laws] need to change," Prime Minister Jacinda Ardern says. "Regardless of what activity may or may not have happened with gun retailers, they will change."
It's an urgent response to a horrific crime.