On his first day off, Tuesday April 27th - is the day our health authorities expect he could have been infectious in our community.
One of the food delivery workers also attended cooking classes at the Perth College of Business and Technology on April 27 and 28, Mr McGowan said.
Western Australian Premier Mark McGowan said publicly yesterday that a full lockdown was not necessary at that stage because Perth had still been subject to earlier COVID-19 restrictions including mask wearing and social distancing during most of the worker's infectious period. The ministry has contacted all but two of the 397 people.
WA Premier Mark McGowan says he hopes to avoid another Perth lockdown, after no new community cases were detected overnight. Those people are considered casual plus contacts and have been asked to self-isolate and get tested five days after their exposure.More news: Dozens killed in stampede at Israel pilgrimage site
Two people he lives with have since contracted the virus.
"CCTV vision is being reviewed, however there is no clear explanation at this point as to how this security guard could have been infected", Mr McGowan said.
Cafes and restaurants will return to "pretty much business as usual" but hospitality venues must comply with either the two-square-metre rule or 75 per cent capacity.
Scheduled flights between WA and New Zealand have been cancelled, including a flight from Perth which had been due to land in Auckland at 5.50am on Sunday morning.
Anyone who had been in Perth since April 27 is advised to check the Western Australian Government website for locations of interest and advice regarding isolation and testing.More news: Stressing diplomacy, Biden says not seeking conflict with China, Russia
New Zealand quarantine hotels have shared recreational, smoking and exercise areas while those in Australia are confined to their rooms for the duration of their 14-day stay.
Flights between New Zealand and Western Australia were suspended less than a week later, when the Perth and Peel regions were sent into a three-day lockdown after recording a case of community transmission on April 23.
The NZ government is also advising anyone who has arrived into the country from the WA capital in the last four days to check the exposure sites and self-isolate immediately if exposed.
Anyone now in Australia, including New Zealanders, who were at a location of interest can not travel to New Zealand within 14 days of exposure.
The Ministry of Health will provide another update about the situation regarding Western Australia on Sunday.More news: Registration for 18+ age group from today
Perth and Peel remain "orange" zones under Victoria's traffic light border restrictions, meaning travellers must apply for an exemption before being permitted to enter the state.