The Australian state of Victoria will go into a snap lockdown at midnight tonight, as the Melbourne Aiport's Holiday Inn Covid-19 cluster built to 13 cases, with hundreds of close contacts identified.
All of the 13 cases are the UK variant of the virus, Newshub reported today.
This means Victorians will only be allowed to leave home for one four reasons: essential supplies, caregiving, exercise or essential work.
Exercise and shopping are to be limited to 5km from home, face masks will be mandatory and public gatherings and home visits will be banned. Schools will close but remain available to the children of those who have to go to work.
State Premier Daniel Andrews, in a media stand-up today, said "It is the advice to me that we must assume that there are further cases in the community than we have positive results for, and that it is moving at a velocity that has not been seen anywhere in our country.
"Because it is so infectious, and moving so fast, we need a circuit breaker."
The new cluster prompted Victoria's cabinet to meet on Friday morning (NZ local time) to discuss what actions should be taken.
Australian Prime Minister Scott Morrison urged Victoria's government to take "proportionate, short-term" action in addressing the threat of the cluster.
"Look at Perth, look at Brisbane, look at Sydney - proportionate short-term responses and they're back on deck."
As the state has already been through a tough 15-week lockdown last year to stamp out the virus, stage four restrictions will only last 5 days and are scheduled to end at midnight next Wednesday.