Victoria will enter a "short, sharp" five-day lockdown in an effort to contain a growing outbreak of the Delta variant of COVID-19.
Premier Daniel Andrews confirmed the lockdown will begin at 11.59pm on Thursday, after two more local COVID-19 cases were recorded this afternoon.
People will only able to leave home for five reasons - to shop for food and essential items, provide or receive care, exercise, work or study if they are unable to from home, and to get vaccinated.
A five-kilometre travel limit will also be reimposed for exercise and shopping, as will compulsory use of masks both indoors and outdoors.
All non-essential retail will close but essential stores like supermarkets, bottle shops and pharmacies will remain open, with shopping limited to one person per day, per household.
Cafes and restaurants will only be able to offer takeaway.
Childcare and kinder will stay open but schools will close, except for a small cohort of students.
The lockdown will end at 11:59pm on Tuesday, though regional Victoria will be able to reopen earlier if it is safe to do so.
Mr Andrews said the state's contact tracers were moving faster than they ever have, but haven't been able to keep up with the spread of the Delta variant.
"We've got no choice. We have to do this, otherwise, it will get away from us. We don't want this getting away from us and being locked down for months," he told reporters.
"We want to deal with this with a short, sharp lockdown. Decisive action, not waiting, not dawdling, not delay.
"Hard and fast, you only get one chance. Now is our time."
It is the fifth lockdown for Victoria since the start of the pandemic and the third in 2021.
There are now 18 active COVID-19 cases in the community associated with two outbreaks in Melbourne, both originating from NSW.
Of greatest concern to authorities are three cases who tested positive after attending an AFL match between Carlton and Geelong at the MCG on Saturday.
COVID-19 Commander Jeroen Weimar said the cases appear to be linked to an infectious Maribyrnong man who attended the match and was seated in the MCC member's reserve on level two.
But he said the trio are not known contacts of the infected man and it appeared to be a case of "stranger-to-stranger transmission".
"They were sitting in very different parts of the ground. There's no obvious relationship between them. The interviews and discussions are ongoing," Mr Weimar said.
The infected man, aged in his 60s, attended the game with his friend, a teacher from Bacchus Marsh Grammar school who lives in Barwon Heads.
The teacher and two of his family members, a nine-year-old child and a man in his 60s, have also subsequently tested positive for COVID-19.
Both Bacchus Marsh Grammar and Barwon Heads Primary School, as well as St Patrick's Primary School in Murrumbeena, have been closed.
There are more than 75 exposures sites across Melbourne and regional Victoria, with some 1500 primary close contacts and 5000 secondary contacts self-isolating.
Opposition Leader Michael O'Brien said he was concerned lockdowns were being used as a "first response" rather than a last resort.
"We can't keep going into lockdown every time we get 10 or 12 cases in the community," he said.
Victorian locations where there is a risk you may have been exposed to COVID-19: https://www.coronavirus.vic.gov.au/exposure-sites
Australian Associated Press