Three men in their 70s have become the first Victorians to die from coronavirus and more people in the state could die from the condition in the coming days.
The men had pre-existing health conditions, but Victoria's Chief Health Officer Brett Sutton said they would have been at risk anyway because of their age.
Professor Sutton said Victoria had been lucky not to have any coronavirus deaths until now, and that there's "every possibility" that more could happen in the coming days.
"We've talked about it in the most serious terms for good reasons," he said on Thursday.
"These three tragic deaths are now a genuine illustration of what coronavirus does.
"We absolutely have to get infections down, because infections down means fewer deaths."
Health Minister Jenny Mikakos stressed the need for everyone to help prevent such deaths, as the number of confirmed cases of COVID-19 in Victoria swells to 520.
"We all have a role to play in the fight against coronavirus and this means we must all take very seriously the message that we must stay home unless it is absolutely essential to leave your home, you must stay at home at every opportunity," she told reporters.
There were 54 new cases confirmed on Thursday - a slight decrease on previous days - but Prof Sutton stressed that does not mean the community can become complacent
Of the state's 520 cases, 14 are in hospital - including three in intensive care - and 149 people have recovered.
More than 26,900 Victorians have been tested to date.
Prof Sutton said he has provided "frank and vigorous advice" to Premier Daniel Andrews and the state government about going hard on shutting down parts of the community to curb the spread of the virus.
The comments come a day after Mr Andrews warned he may implement further measures to fight the spread of the coronavirus.
The Police Association has also called for a state of disaster to be declared, which would give its members greater powers during the health emergency.
Victoria Police Chief Commissioner Graham Ashton said the need to declare a state of emergency will depend on how people behave, noting that so far people largely have followed restrictions.
Mr Ashton said about 300 police were out on the beat on Thursday doing spot checks on people self-isolating.
Of the 88 checks conducted so far, 70 people were home, seven people were not, and a couple of people provided the wrong address details to the Australian Border Force.
"We're obviously following those up," Mr Ashton said.
Individuals face fines of up to $25,000 and businesses face $100,000 fines for breaching isolation restrictions.
About 400 police staff are self-isolating as a result of potential contact with infected people, while two officers were earlier diagnosed with COVID-19.