A Perth hotel quarantine security guard and two of his housemates have tested positive to COVID-19.

The man – known as case 1,001 – worked at the Pan Pacific Perth and may have been infectious in the community since April 27.

The security guard and his housemates are being moved into hotel quarantine and urgent contact tracing is underway.

Premier Mark McGowan made the announcement at an emergency press conference this afternoon, where he revealed masks will again become mandatory inside and outside the home for people in the Perth and Peel region.

He said because the cases were picked up early the state would avoid moving into another snap lockdown.

However, he has warned a lockdown could still be possible once more information comes to light.

“This is an extremely difficult situation we’re dealing with, we’re effectively in a holding pattern, and I hope we can avoid going back into lockdown,” he said.

The infected security guard visited a number of places across the metropolitan area including a shopping centre in Stirling, a Coles in Balcatta and a Mirrabooka Mosque.

Anyone who has been to a possible exposure site is being urged to get tested immediately and isolate.

CCTV is being reviewed to determine how the security guard contracted the virus.

He had received a first dose of the COVID-19 vaccine.

Another emergency press conference will be held tomorrow morning.

Press PLAY to hear more.

(Photo: Matt Jelonek/Getty Images)