Talks are under way to convert the Western Australian holiday hotspot Rottnest Island into a COVID-19 quarantine zone as the state's border closure approaches and the number of confirmed cases continue to rise.
Premier Mark McGowan announced on Sunday that entry to WA would be restricted via road, rail, air and sea from 1.30pm local time on Tuesday.
There will be exemptions for health, emergency, defence and policing personnel, certain mining industry workers, flight crews and those delivering essential goods via ports and trucks.
Exemptions will also be granted on compassionate grounds and where people live near border communities.
Unless exempted, arrivals from interstate will be ordered to self-isolate for 14 days.
"Western Australia is now in a war, the type of war we have never seen before," Mr McGowan said.
"These are extreme steps but these are extreme days."
Travel within the state is still being allowed for now, excluding remote Aboriginal communities, "but that may change".
Hotels in Perth and army barracks could also be used for those "who can't quarantine or won't", the premier said.
Critical mining, and oil and gas operations will continue, with about 2,500 resources sector workers continuing to travel to WA from interstate.
The coast-to-coast Indian Pacific train will not take passengers but may move cargo.
Medical professionals have repeatedly called for schools to be closed and there are concerns about Perth's Crown Casino remaining open.
WA has recorded 120 confirmed coronavirus cases, including the nation's first COVID-19-related death, 78-year-old James Kwan, on March 1.