Victorians are in lockdown for the third time amid fears the highly infectious UK strain of coronavirus has spread in the community.
Schools and non-essential retail shops will be closed with some exceptions, and Melbourne will return to its August lockdown settings.
There will be four designated reasons to leave home, including shopping for essential items, care and caregiving, exercising for two hours per day and work and study that can't be done at home.
The five-kilometre rule will also be reinstated - where residents can't travel more than five kilometres from their home, with some exceptions.
One new locally acquired coronavirus case was recorded on Friday, taking the total number of active cases in the state to 20.
"Victorians have been through this before, we know that these tactics work," Mr Andrews said on Friday.
"I know this is not the news Victorians wanted to hear today, I know this is not the place we want to be in...We have to make difficult decisions to maintain what we have built."
"If we wait for this theory that it might be out there, there might be more cases than we know about, it would be too late, and then we would face the chance of being locked down until a vaccine is rolled out," he added.
Religious gatherings and services are not permitted, funerals will be limited to 10 people and weddings will not be permitted.
Victoria's cabinet met on Friday morning to discuss the snap lockdown in response to the Holiday Inn outbreak which had grown to 13 confirmed cases on Friday afternoon.
Six of the cases in the Holiday Inn outbreak have been confirmed to be the more infectious UK variant of coronavirus, with the working assumption being that all 13 cases may be the UK variant.
Mr Andrews said the "hyper-infectivity" of the UK variant meant the virus was moving so fast - it presented an enormous risk to the Victorian community.
"We are having cases test positive, by the time we find that case as positive they have already infected their close contacts," he said.
"This is not the 2020 virus, this is something very different,".
"It is moving at a velocity that has not been seen anyone in this country in the last 12 months," he added.
Health Minister Martin Foley said the lockdown was needed to prevent a devastating third wave.
"We have an important need to get ahead of this virus and to have a short, sharp circuit breaker so we don't have a third wave.
"A third wave would be catastrophic, particularly for our vulnerable Victorians."
Some 905 Victorians have been identified as close contacts of confirmed cases.
Mr Andrews said the reason the same rules would apply across the state of Victoria was to stop Melburnians travelling to the regions.
It comes as Prime Minister Scott Morrison urged the state government to take a "proportionate" response to the recent outbreak.
“A proportionate response that enables those, the tracers and others, to be able to get on top of it and get the same successful result we have seen in other states,” he told reporters on Friday morning.
Earlier Mr Morrison told 3AW radio that he supported calls for a "short sharp" lockdown in the state.
A total of five new cases were confirmed by the Health Department on Thursday, including two announced at 11pm.
"Both are household primary close contacts of previously announced cases," the department posted on Twitter.
The cases, which will be included in Friday's official figures, also include a female assistant manager at the hotel and two men, both partners of female workers who earlier tested positive to COVID-19.
One of the men may be linked to Camberwell Grammar School in Melbourne's east.
"We believe there will be some additional exposure sites emerging from some of these cases," Victoria's COVID-19 Testing Commander Jeroen Weimar said on Thursday.
"That work needs to be done over the coming hours."
The Brunetti cafe in Terminal 4 at Melbourne Airport was listed as an exposure site early on Friday morning after it was visited by an infected person on 9 February between 4.45am and 1.15pm.
The exposure raises fears the virus may have travelled interstate.
Anyone who visited the cafe during that time needs to get a COVID-19 test and isolate for 14 days.Mr Weimar said authorities were "right on top" of the outbreak, picking up cases among identified contacts who had tested negative just days earlier.
Quarantining hotel guest at the Holiday Inn near the Airport are moved to a new location in Melbourne on 10 February, 2021. Source: AAP
His "working assumption" is all the cases have been infected with the more transmissible UK variant of COVID-19, complicating the containment job for officials.
"This is by no means over," Mr Weimar said.
"We are still in the opening quarter of the Holiday Inn outbreak, I'm afraid. We've got a lot more work to do."
The cluster has prompted several states to tighten their borders to travellers from Greater Melbourne.
South Australia locked out travellers from the Victorian capital at midnight on Thursday, while Queensland will bar entry to visitors of the city's exposure sites from 1am on Saturday.
Western Australia also announced its hard border to Victoria would be extended for at least another seven days.
In addition to strengthened interstate borders, the outbreak has forced the hotel's closure, a pause on a planned increase to Victoria's weekly international traveller's cap and multiple health alerts for potential exposure sites.
An undeclared nebuliser, used inside the room of an infected family of three, is the suspected cause of the outbreak.
People in Australia must stay at least 1.5 metres away from others. Check your jurisdiction's restrictions on gathering limits. If you are experiencing cold or flu symptoms, stay home and arrange a test by calling your doctor or contact the Coronavirus Health Information Hotline on 1800 020 080.
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