Andrews has written a strongly worded statement on the triple digit spike in virus cases in his state, warning the virus can "spread like wildfire".
Andrews said the increase of 108 new cases was the second biggest the state had seen since March 28.
"As these figures show, we are still on a knife's edge. Rather than spread across the state, we know many of these cases are located in specific communities," Andrews said.
He said "targeted, swift action is stronger than ever before".
"The close confines and the shared community spaces within these large apartment blocks means this virus can spread like wildfire.
"And just like fire, we need to put a perimeter around it to stop it from spreading."
On Saturday, Andrews announced the closure of nine public housing towers "effective immediately" in hot zone suburbs. The towers were linked to clusters of coronavirus cases.
"Just as we've done with similar outbreaks in closely confined settings like aged care, the only people coming in and out will be those providing essential services."
Andrews said the closing of the towers would be in place for the following five days while they tested residents.
The state was also expanded their lockdown zones to postcodes 3031 and 3051 at 11.59pm on Saturday night.
"I know this is big. And I know this is unprecedented.
But as always with this thing, an unprecedented challenge requires unprecedented action," Andrews added.
"This virus is dangerous. It's indiscriminate.
"And it has the potential to undo everything that's been achieved."
When asked how big the "cluster" of cases is in Victoria, the state's Deputy Chief Health Officer Dr Annaliese van Diemen said at least 23 of today's cases 108 new cases had been linked to a known cluster. She said she expected that number to rise before the end of the day.
"I know that today we have linked at least another three, if not four or five cases to this cluster across the two groups of housing estates," Dr van Diemen said.
"There was at least 23 at the start of today. So, I suspect it will be up to 30 by the end of the day. There's constant interviews and linking happening throughout the day."
'I am concerned': Acting Chief Medical Officer addresses Victorian virus spike
Acting Chief Medical Officer Professor Paul Kelly said the issues in Melbourne are "front of mind" for Australians but he added all of Australia was here to assist the state as they tackled the issue.
"I am concerned," Professor Kelly said but added testing had expanded in the state. He urged Victorians to engage with testing.
Kelly said on Saturday evening that he'd called an unscheduled tele meeting with the Australian Health Protection Principal Committee (AHPPC) tonight to discuss the issues in Victoria, but said said Australia was equipped with clinical and contact tracing resources to assist the state.
Kelly said he knew the tower blocks in Melbourne well and he supported the Premier's decision to close the towers while they conducted testing on the residents.
The AHPPC will also be meeting at 6pm tonight, and Prof Kelly said they'll be discussing the situation in Victoria.
Kelly said the decision to expand the lockdowns to new suburbs in Victoria was based on an "increase on case numbers" in "hot spot areas".
The latest news comes as New South Wales have just reported a dramatic increase in virus numbers, as 189 historic cases from Ruby Princess crew members are added to the state's tally.
But NSW Health have just confirmed they have been added to the tally months after they occurred, taking the total number of cases in Australia to 8255.
