All New Zealanders, apart from essential service workers, are being asked to stay at home in a bid to halt the spread of Covid-19.
An epidemic notice is in place, a state of emergency has been declared, and police are empowered to enforce rules intended to stop the spread of the disease.
Another 36 Covid-19 cases were confirmed yesterday, bringing the national total to 102.
After scientists confirmed community transmission of the disease was now happening in New Zealand, the Prime Minister immediately raised the national alert level to 3, rising to 4 by midnight tomorrow.
That Level 4 status is expected to remain in place for at least four weeks.
It will mean the closure of all but essential businesses, including schools, most shops, bars and restaurants.
All indoor and outdoor events are banned.
Vital food, transport and infrastructure services such as supermarkets, petrol stations, energy providers and medical professionals will remain open, as will banks.
Public transport will be available for essential tasks.
"If community transmission takes off in New Zealand the number of cases will double every five days," Ms Ardern said.
"If that happens unchecked, our health system will be inundated, and tens of thousands New Zealanders will die."
The country had a window of opportunity to stem or possibly stamp out community transmission and it needed to take it, Ms Ardern said.
"For the next wee while, things will look worse before they look better.
"In the short term the number of cases will likely rise because the virus is already in our community, but these new measures can slow the virus down and prevent our health system from being overwhelmed and ultimately save lives.
"We will get through this together, but only if we stick together. Be strong and be kind."
Despite the Prime Minister stressing supermarkets and petrol stations would remain open and a plea to not panic buy, people throughout the South flocked to both within minutes of her 1.45pm briefing to stock up on supplies.
Waitaki Mayor Gary Kircher called police to an Oamaru supermarket yesterday to help control crowds of shoppers.
"They were getting just inundated with people who were obviously frantic," Mr Kircher said.
"People don’t have a good understanding of what’s going on and end up panicking, but I think as time goes on the reality will sink in that, actually, things like food, cleaning products, water and everything will still be readily available and they’re able to get it."
Phone services also quickly became overloaded, with Spark urging people to use other means of communication.
Four further southern Covid-19 cases were confirmed yesterday by the Southern District Health Board.
Only one of those cases, a Dunedin woman in her 20s who had recently returned from the United States, seemingly tallied with the Ministry of Health’s earlier-released figures for national cases.
The four new patients took the total of confirmed southern cases to 13, along with one other probable case.
The other new cases were a West Otago woman in her 50s, a Dunedin woman in her 30s, and a Wanaka teenager.
All four individuals were "mildly unwell" and at home in self-isolation, an SDHB spokeswoman said.
The number of southern cases may yet surge, as health officials continue contact tracing people who attended the World Hereford Conference in Queenstown last week.
Four people who were at the 500-plus strong gathering have since tested positive to Covid-19; several people, including a church congregation in Palmerston, have been ordered into self-isolation.
The board was contacting people around New Zealand who had attended the conference and asking them to self-isolate.
The board also issued an alert that people in Wishbone Cafe at Dunedin Public Hospital (March 15, 1.30pm-2pm), Mitre 10 South Dunedin (March 15, 3pm-4pm) and Integrated Health and Physio at Dunedin Hospital (March 16, 8am-8.45am) might have been in contact with someone with Covid-19.
Any person in that situation was considered a casual contact and at low risk of contracting the disease.
Health Minister David Clark said it was vital that initiatives such as social isolation and contact tracing continue, and urged people to co-operate with the Government’s attempt by moving to Level 4 to break the chain of community transmission of Covid-19.
"These are necessary measures in these unprecedented times ... everything you will all give up over the next few weeks will literally save lives."
The move to Level 3 then 4 saw Finance Minister Grant Robertson announce further, sweeping moves designed to bolster the economy.
Those included all firms being eligible for the wage subsidy scheme announced last week, the $150,000 cap on that scheme being lifted, and a freeze on all rent increases.
Further moves — including new wage support initiatives and support for mortgage payments and business finance — were agreed in principle, but the details were still being worked through, Mr Robertson said.
— Additional reporting Rebecca Ryan
