The Australian city of Perth has begun a snap five-day lockdown after a security guard working at a quarantine hotel tested positive for coronavirus.
Western Australia – the state of which Perth is the capital – had not had a case of locally acquired coronavirus for 10 months.
The lockdown began at 18:00 (10:00 GMT) and runs until Friday night.
Schools, restaurants, bars, cinemas and gyms have been ordered to close.
Only essential travel is allowed and masks must be worn.
People in the city of two million – along with people living in the nearby Peel and South West regions – must stay at home, except for essential work, healthcare, food shopping or exercise, said Western Australia state Premier Mark McGowan.
A scheduled return of schools on Monday has also been delayed by a week.
“I know for many Western Australians this is going to come as a shock,” Mr McGowan said at a news conference. “We cannot forget how quickly this virus can spread, nor the devastation it can cause.
“Our model is to deal with it very, very quickly and harshly… so that we can bring it under control and not have community spread of the virus as you have seen in other countries around the world,” he added.
Mr McGowan said the guard may have the UK variant of the virus: “We are told the guard was working on the same floor as a positive UK variant case.” The guard and his family have been placed into quarantine at a state-run facility, he added.
Leaders of other states and territories have also been contacted and advised not to allow people to travel into the state.
Australia has recorded nearly 29,000 cases and 909 deaths since the pandemic began, for a populations of about 25 million – far fewer than many other countries.
In recent months in particular, the nation has taken swift and aggressive actions to contain outbreaks at their source, and it currently has a travel ban in place preventing residents from overseas travel.
Earlier this week, Australia also suspended a travel bubble with New Zealand after its first Covid case in months was confirmed to be a more contagious variant.
It has now reopened the travel bubble with New Zealand. Travellers to Australia will be screened before and after flights for the next 10 days, but will no longer be required to enter quarantine.
Until the Perth case, Australia had not had any locally acquired infection for the past 14 days. Its only infections had been in returned overseas travellers in hotel quarantine.
On Thursday, Australia was ranked eighth in a list of nations which had responded best to the virus. New Zealand and Vietnam topped the list from the Lowy Institute think tank.