New Zealand PM Jacinda Ardern said the suspect had a gun licence, obtained in November 2017, and owned five guns.
Earlier on Monday, gun retailer Gun City said it had sold four weapons to the alleged gunman online, but it did not sell him the high-powered weapon used in the mosque shootings.
CEO David Tipple told a news conference in Christchurch it had only sold him A-category weapons.
Under the country’s gun laws, A-category weapons can be semi-automatic but limited to seven shots. Video footage of the attacks appeared to show the gunman with a larger magazine round, which is also available legally.
There are an estimated 1.5 million privately owned firearms in the country.
Since the attack there have been calls for semi-automatic weapons to be banned, a regulation that exists in Australia and Canada.
Previous attempts to tighten gun laws have failed due to a strong gun lobby and a culture of hunting.