Victorian Premier Daniel Andrews announced a state of disaster would be in place from 6pm on Sunday as 671 new COVID-19 cases were recorded.
Regional Victorians must now stay at home except for the four reasons – food, essential goods and services, care giving, medical, compassionate reasons, work or study or exercise,
"From the outset of this second surge, our aim has been to protect regional communities. By putting a ring around the city, we want to protect the entirety of our state," Mr Andrews said in a statement.
"For the most part, it’s worked. But as we know, this virus doesn’t discriminate, and its only goal is to spread.
"Based on the current numbers, it’s clear there is a real and growing threat in some regional communities.
"The thought of this virus getting into regional aged care – and wiping out entire generations within our regional communities – is something that keeps me up at night. I know I’m not alone.
"We cannot let this virus tear through regional aged care in the way it has with private sector aged care in Melbourne.
"We cannot let it mean more Victorians in hospital beds. More Victorians hooked up to machines just to breathe.
"And more Victorians – more grandparents, parents, sons, daughters, partners and loved ones – choked to death by an invisible enemy.
"That’s not something I’m willing to accept. I don’t think it’s something any of us are willing to accept.
"We must do more. We must go harder. It’s the only way we’ll get to the other side of this."
Students will go to school as normal on Monday before a pupil free day on Tuesday.
All classes will return to remote learning on Wednesday, with specialist schools the exception.
Melbourne will enter stage four restrictions with a number of new rules in place.
There will be a curfew in place from tonight between 8pm and 5am with exemptions for work, caregiving, medical and compassionate reasons.
Those living in Melbourne can now only exercise for one hour daily within 5km of their home, with one other person – no family or share house groups.
Under changes to shopping, only one person per household can leave the home to travel within 5km of their home.
All childcare centres will be closed with exemptions available for vulnerable and children of permitted workers.
Visits to intimate partners are still allowed outside 5km.