Victoria's health authorities fear the state is now on course to fall into the same coronavirus crisis crippling NSW after staggering scenes of thousands protesting in Melbourne's CBD.
Even before the crowds converged, 77 new cases were confirmed on Saturday and Premier Daniel Andrews announced Melbourne's lockdown would be broadened to include the entire state.
Despite a heavy police presence and warnings of the potentially devastating spread of COVID-19 it may cause, more than 4000 people flooded streets in the city centre to oppose the extension of the state's lockdown.
More than $1 million in fines will be handed down, at least 218 people were arrested, and six police officers ended up in hospital as authorities lambasted abhorrent scenes.
"The behaviour seen by police was so hostile and aggressive that they were left with no choice but to use all tactics available to them," a Victoria Police spokeswoman said.
"For the first time during lockdown protests, police were forced to use a range of non-lethal options including pepper ball rounds and OC foam cannisters in an effort to disperse the crowd.
What they claimed was "a freedom demonstration" was "anything but", Victoria Police Chief Commissioner Shane Patton said. "It's just selfish."
The spokeswoman said "the majority of those who attended came with violence in mind".
The fear now facing health authorities is that cases will explode and contact tracers will be unable to control fresh outbreaks.
Mr Andrews had warned on Friday that if people ignored lockdown restrictions this weekend "well then next week it will be like Sydney", where cases have boomed to hundreds of new infections every day.
COVID-19 response commander Jeroen Weimar said the hospitalisation numbers showed a disturbing trend.
There are 18 Victorians in hospital, and eight in intensive care, with two on ventilators.
"We note these numbers are starting to rise," Mr Weimar said.