Two million people are now in lockdown after a third person tested positive to COVID-19 in Perth’s northern suburbs overnight.

The man in his 30s caught the virus from a returned interstate traveller at a Mindarie Brewery.

Speaking with 6PR’s Oliver Peterson Health Minister Roger Cook said they’re still trying to figure out exactly how the man became infected.

“Were still trying to pull all of the pieces of the puzzle together,” he said.

“My understanding is he was actually at the Indian Ocean Brewing Company for a meal as opposed to being on active duty but we’ll get a better idea of his movements today and how he would have contracted it.”

Both partners of the Sydney case and the 32-year-old woman have so far tested negative.

“This is the Delta strain, which is highly transmissible and so we would have expected partners to fall ill as well, so it’s an unusual pattern,” he said.

At this stage the shutdown will last four days, people must stay at home except for essential reasons, however schools will remain open.

Press PLAY to hear the full interview