Parts of Western Australia went into a five-day lockdown Sunday, after a hotel security guard tested positive for coronavirus.

The Perth metropolitan area and the Peel and South West regions of the Australian state are now under "full lockdown," Premier Mark McGowan announced Sunday, with residents only able to leave their homes for essential shopping, medical needs, exercise, and for jobs that cannot be done at home or remotely.

Schools, most businesses, entertainment venues, and places of worship are all closed, and restaurants restricted to takeaway only.

"This is a very serious situation and each and every one of us has to do everything we personally can to help stop the spread in the community," McGowan said.

The Perth metropolitan area and the Peel and South West regions have a combined population of more than 2 million people, with the vast majority living in the state capital Perth.

The drastic measures come after a man in his twenties who worked as a security guard at the Sheraton Four Points, a hotel quarantine facility, tested positive for the coronavirus. Of the four active cases at the hotel, while the man was on shift, two were carrying the United Kingdom strain and one the South African strain of the virus, which are believed to be more contagious than other variants.

"We are told the guard was working on the same floor, as a positive UK variant case," McGowan said. As the man had worked two 12-hour shifts on January 26 and 27, it was possible he had contracted the UK strain, the Premier added, though he said "exactly how the infection was acquired remains under investigation.

"Officials are calling on all people who visited a specified list of venues on a certain date to get tested. All close contacts of the man are required to quarantine for 14 days.

"Western Australians have done so well for so long but this week it is absolutely crucial that we stay home, maintain physical distancing and personal hygiene, and get tested if you have symptoms," McGowan said.

With a population of around 2.76 million, Western Australia has recorded 902 coronavirus cases since the pandemic began, though it currently only has 12 active cases, according to the state's health department. Over 800 of the state's confirmed cases are among international travelers and people who arrived by cruise or other vessels, with less than 100 locally-transmitted cases in total.

Australia has recorded a total of 28,811 cases, with 909 deaths, the majority of which occurred in the southeastern states of Victoria and New South Wales. The country has shown success in controlling the coronavirus through stringent lockdowns and tight border controls, with all international visitors required to undergo testing and quarantine.

Last year, the southern state of Victoria was placed under tight lockdown for almost two months in order to contain an outbreak around the city of Melbourne.

But while the broader measures were effective, officials in the state faced criticism for a "hard lockdown" that was enforced against nine public housing towers in Melbourne. Around 3,000 residents of the towers were not given advance warning of the lockdown, which prevented them from leaving their homes for any reason for over five days.

Last month, an official investigation into the restrictions found they "breached human rights," and were not based on direct health advice.