The Prime Minister is warning that the outbreak of COVID-19 in New Zealand will get worse before it gets better.
Jacinda Ardern announced on Monday that the country's alert level would be rising to 3, before rising again to level 4 - the highest - 48 hours later.
Her announcement came as authorities said two of the country's 102 cases were being treated as coming from community transmission.
Monday's announcement means that as of 11:59pm on Wednesday New Zealand will be going into lockdown.
"It will get worse before it gets better because we have a lag from the time that people have it to the time that they're symptomatic and then if they've passed it on there will be those then that have a lag in coming through," Ardern told The AM Show on Tuesday.
She said New Zealand had learnt from the experiences of other countries how important it was to act early before community transmission got out of hand.
"We do have a window of opportunity and we are using it."
"Rather than be in a position where your health services are overrun and people are losing their lives and then move into lockdown, move early - that's your best chance of saving lives and it's your best chance of actually being in it for a shorter time as possible."
The country's lockdown will last at least four weeks. All non-essential businesses will close and Kiwis must go into self-isolation.
"If everyone reduces down their contacts, stays at home, that's one less person that's at risk of picking it up who's less likely to pass it on to three other people and then three other people and then three other people - which is roughly the transmission rate," Ardern said.
"So everyone needs to play their part, and please do. It's not just about your life, it's about others'."
In anticipation of more cases, the health system's ICU capacity had effectively been doubled, Ardern said, bringing the total number of beds to around 500.
So far, our hospitals are coping, but Ardern warned that a mass outbreak such as in Italy could place a massive strain on our health system.
"This is a pandemic, a global pandemic. No health system in the world would be equipped to deal with a situation where every person would get care if they are completely overrun with cases and they have a high transmission rate."