"I know that the virus re-emerging in our community has caused alarm and the unknown is scary. That causes anxiety for many of us," Bloomfield said.
The family who had tested positive was in isolation at home in south Auckland and a decision hadn't been made about whether they would be moved to a quarantine facility, he said.
"We are working hard to put together the pieces of the puzzle as to how this family got the virus. We are testing all close and casual contacts," he said.
Bloomfield said there were no results of tests of other members of the family to report yet.
Once authorities found about the positive test, both the case and the family were contacted and isolated at home and all were tested. The trip to Rotorua took place last weekend. The woman and one of the pre-schoolers had tested positive, Bloomfield said.
"The family visited a number of tourist venues while in Rotorua," he said.
Given members of the family travelled to Rotorua and went to work while symptomatic, Prime Minister Jacinda Ardern said this reinforced why it was so important that if you are sick you stay home.
Close contacts of the family are required to stay in isolation for 14 days regardless of a negative test.
Surfaces in a coolstore workplace are being tested to see whether freight or something else may have been the origin of the new cases.
There are between 6000 and 7000 people who work at managed isolation facilities and at the border who will be tested.
"We are very confident we didn't have any community transmission for a very long period," Bloomfield said.
"I'm sure I felt like every other New Zealander, of course I was disappointed," Bloomfield said of the moment he got the text message saying there was a confirmed case in the community.
"If there is one place in the world where people can have hope we can get on top of this it's Aotearoa New Zealand," he said.
There are reports a woman who travelled from New Zealand to Japan was asymptomatic but tested positive on arrival. Bloomfield is seeking more information.
Longer in level 3?
The decision around staying longer in alert level 3 will be based on whether the source has been identified and whether more positive cases appear that can't be linked to a source. At this stage, Auckland will be in alert level 3 until midnight Friday.
"We continue to have arriving New Zealanders that are all operating in a level 4 environment, so there is no reason why we can not continue to do that."
Ardern wouldn't give a time on when a decision on extending alert level 3 in Auckland would be made.
"I have huge sympathy for [the anxiety of going back into alert level 3]," Ardern said.
"This is unsettling. My advice is 1737 is a helpline that is available and I encourage people to reach out to their friends and neighbours," Ardern said.
"We do have a plan, we are rolling it out and we have very, very good people who are working on this with a huge amount of effort to limit the affects of this as much as possible."
Roadblocks go up in Auckland
Meanwhile, police have confirmed they will be staging road blocks after midday today to enforce the level 3 lockdown in Auckland.
Police Commissioner Andrew Coster said checkpoints would operate around the region's Super City boundaries.
We will be visible around supermarkets and places where communities need the assurance of police presence."
From midday, police would also be operating nine checkpoints at exit points just inside the regional boundaries, largely based on the Auckland Super City boundaries," Coster said.
"We will be stopping vehicles and questioning drivers, but as has been our approach through the Covid-19 response, our first focus will be on educating people and ensuring they are aware of the new restrictions.
"We have issued a reminder to our staff that they need to be exercising good hygiene and social distancing practices, and we have issued a directive to our Auckland staff that they must wear masks when dealing with the public, and other PPE gear as necessary."
Coster said the Defence Force could also be used to staff the checkpoints.
"For the rest of the country, this is not new territory for people and hopefully there is a strong community willingness to abide by the restrictions of alert level 2."
Bloomfield was texted about the cases at 2.40pm yesterday. He called the Counties Manakau DHB chief executive about 2.45pm and they had a zoom meeting about seven minutes later, he said.
As soon as the person tested positive at 2.30pm, the person and everyone around them went into isolation, Ardern said. Contact tracing began immediately.
Ardern and Bloomfield reiterated the timeline of when they were told of the positive test result yesterday afternoon before the announcement of lockdown at 9.15pm yesterday.
Genome sequencing may be able to reveal where the new cases originated from and whether it was connected to an isolation facility.
130 colleagues of positive case isolating in Auckland
.
One hundred and thirty people who work with the man who tested positive in a finance company are considered close contacts.
Three of the man's contacts are symptomatic and isolating at home.
"None of the workplaces where there is a risk are public-facing," he said.
There are four locations of a workplace across Auckland that have been shut down. A Mt Wellington location is where one of the confirmed cases works.
One hundred and forty people are standing by to support Auckland Regional Public Health with contact tracing. Healthline is very busy and has additional staff on, Bloomfield said.
Tens of thousands of people are expected to be tested over coming days.
Bloomfield said the public health department wanted to see if the environment of the workplaces contributed in any way to any spread of the virus.
"We know the virus can survive within refrigerated environments for a very long time."
The virus could have possibly been brought in on refrigerated goods.
"The best thing we can all do now is face this together ... to comply with key public health messages ... and we are also recommending the use of masks, particularly in Auckland," he said.
We have seen in other countries and jurisdictions where a resurgence occurs that it is incredibly important to act early," Bloomfield said
No decision on possible election delay
Parliament was due to dissolve today at 11am but it has been deferred by at least a few days.
Options around the election are being explored and no decisions have been made about whether it will be delayed or not.
The election could still be held on September 19 and it can be held under alert level 2. The date could be moved to any date before November 21. Things get complicated if it needs to be pushed further out than November 21.
Covid would continue to exist within the world for the foreseeable future, Ardern said, and other countries had navigated elections in a Covid world.
When to get a test - PM's plea
If you have visited Auckland in recent days you should remain vigilant for any symptoms and there is no requirement for self-isolation at this stage, Ardern said.
"If you have any symptoms then do get tested. But, if you have no symptoms and you don't work in [managed isolation facilities] or at the border and you're perfectly healthy then don't," Ardern said.
Extra precautions were needed to look after elderly New Zealanders, so all aged-care facilities would close their doors, she said.
Ardern said it was primarily casual contacts being assessed in Rotorua at this stage.
"In order for us to trace where this outbreak stems from it is really important we increase the number of people being tested, but that doesn't mean we want to test people across Auckland who have no symptoms," Ardern said.
Healthline has received more than 2000 calls since last yesterday.
If you have general questions, please don't call Healthline, Ardern said.
"Wash your hands. Stay at home if you're sick and get a test if you're symptomatic."
"I know how hugely frustrating this situation is for every one of our team of five million," Ardern said.
"Please as always, stay kind look after one another and please stay tuned as we update you."
There is a good supply of swabs and PPE, Bloomfield said. DHBs will be pushing out additional PPE and swabs to ensure there is no shortages.
Cover up - when to wear a mask
"If you are in Auckland please cover your face if you leave your home," Ardern said.
"A mask or any face covering such as a scarf or bandana will suffice. While we are not mandating their general use at this stage, we're strongly encouraging their general use in the Auckland region."
Countdown and Foodstuffs have supplied masks and five million of the Government's general supply is being distributed across the country.
If your supermarket doesn't have any available, you can fashion your own at home.
Masks must be worn on flights leaving Auckland. That is the only place masks are mandatory.
The rules for Aucklanders under alert level 3
Aucklanders should continue to stay in their household bubbles. Only the children of essential workers can go to school. Visitors can't be invited into homes. Physical distancing must be used when out on essential trips like to pharmacies or supermarkets.
Businesses can trade without physical contact with customers, but customers can't enter premises.
Supermarkets, dairies, petrol stations can have customers. Retail is possible through delivery or click and collect.
Lockdown for Auckland looms
Aucklanders are scrambling to prepare for the looming level 3 lockdown from midday today, and lengthy queues are forming outside supermarkets and Covid-19 testing centres.
Police road blocks will be set up at entrances to the Auckland region. The Government confirmed this morning it was working with lawyers on a legal notice to make masks mandatory for Aucklanders to wear while out and about in public.
Supermarkets are rationing essential items to avoid stockpiling.
Air NZ will require all travellers flying from Auckland to wear masks.
Economists are warning at least another three days of lockdown will be devastating for businesses: an estimated 28 per cent of Auckland's workforce cannot operate under level 3 - that's about 250,000 jobs.
Last night Ardern and Bloomfield announced a man in his 50s tested positive for the virus and they couldn't immediately find a connection to the border or managed isolation facilities.
Three others in the man's household have also tested positive. The family are isolating and have been offered a move to a quarantine hotel.
Auckland will move to alert level 3 at midday today until midnight on Friday, while the rest of the country will move to alert level 2 for the same period.
This morning Health Minister Chris Hipkins said the Government would be testing about 50,000 people by the end of the week.
"We will know a lot more in 72 hours than we do now," Hipkins said.
Hipkins told RNZ the Government was working with lawyers on a notice to make masks mandatory for Aucklanders, which will be issued at midday.
He also confirmed work colleagues of one of the family members were showing symptoms. There are reports at least two colleagues are affected so far.
He said it was a "relatively small" workforce affected.
One of the children in the family attends Mt Albert Primary School - the school is closed for 72 hours and the child has been tested, according to a health notice. Officials are awaiting the test results.
Alert level 3
Ardern told media at a hastily arranged press conference last night: "We are asking people in Auckland to stay home to prevent the spread.
"We have done it before and we can all do it again."
It comes after four cases of community transmission from the same family were confirmed yesterday - the first such cases in 102 days. The source of infection is unknown.
Level 3 means public facilities, businesses, restaurants and cafes will shut - as will schools unless they have students whose parents are essential workers - and most people will be required to work from home.
The area covered by level 3 is the Super City - from Wellsford in the north to Pukekohe in the south.