Health Minister Chris Hipkins is reassuring Aucklanders masks supplies in the city are well stocked, as the city enters alert level 3 on Wednesday.
Prime Minister Jacinda Ardern announced on Tuesday evening community transmission of COVID-19 had been confirmed once again, and ordered the country's largest city into alert level 3, and the rest of the country to level 2.
The lockdown would be in place for three days while the source and extent of the outbreak, which was found in South Auckland, was investigated, Ardern said.
Although it is not yet mandatory, Hipkins on Wednesday urged all Aucklanders to wear masks when going out in public.
"Our advice to people in Auckland for now is if you're out doing your supermarket shopping, doing your essential travel - bearing in mind that at level 3 you should only be doing that essential travel - wear a mask," he told More FM on Wednesday.
"You can get masks from the supermarket, you can also order them online, there's a lot of online retailers who will still be delivering them, so do get masks for everybody in the family so if you're out and about in public you can wear them."
He reassured people that there was no shortage of mask supplies.
"My understanding is that supermarkets are well-stocked, the Warehouse is well-stocked, those online retailers are well-stocked. I ordered a mask online about three days ago - one of the reusable ones - and it just arrived this morning. The people who are making them are working around the clock to fulfil the orders."
Ardern on Wednesday said the Government was also releasing five million masks from its central supply to "support distribution into the areas where they're needed".
"We're also looking at provision of masks in, for instance, food parcels and via social services for those who are maybe vulnerable and less able to access masks.
She also reminded people that it was possible to make your own mask if it wasn't possible to buy one.
Hipkins, who is also the Minister of Education, State Services and Ministerial Services, said it was uncertain whether the lockdown would be extended.
"At this point we're asking people to prepare for this week. We will have further advice before the end of the week as to what's likely to happen," he said.
Hipkins said the source of the four new cases of community transmission - which were all in the same family - was a mystery.
"It's a bit of a puzzle, this case, because there's no immediate way to identify how they got it. They haven't come into contact with people at the border or people who have been travelling so that makes it a bit of a puzzle. But we'll know more, a lot more, as the next 48 to 72 hours unfolds."
Director-General of Health Dr Ashley Bloomfield on Wednesday said the family that had returned the positive tests had visited Rotorua during the weekend, and extensive testing was now underway in the city.
Hipkins advised people outside of Auckland to also take precautionary measures.
"For everyone else around the country observe all the precautions that you did at level 2 last time," he said.
"Do everything you can to stop the virus from spreading - so good hand hygiene, maintain your physical distance from other people when you're out in public.
"Obviously do everything that you can to say if I had COVID am I giving this to someone else? And do everything you can to make sure the answer to that is no."
