Climate protesters have brought parts of Sydney to a standstill, blocking key roads and a tunnel during rush hour.
The Blockade Australia activists began disruptions on Monday in protest of "Australia's ecological destruction".
Police said the protesters were "violent" and "erratic" while marching through the city and blocking streets with barricades and bins.
Their actions angered some motorists, with one filmed driving through the protest and colliding with people.
New South Wales Police said more than 10 people had been arrested so far.
They included a woman who used a car to block the Sydney Harbour Tunnel.
"The throwing of bicycles, the throwing of garbage bins, the throwing of other items in the path of police... media... [and] innocent members of the public just walking by will not be tolerated," said Assistant Commissioner Paul Dunstan.
He confirmed police were investigating footage of a car driving through protesters, but said no injuries had been reported.
In the past week, police raided campsites of suspected protest organisers and arrested several other people.
Blockade Australia has promised to bring Sydney to a "standstill" this week - something they say is required for people to take their message seriously.
The woman who blocked the tunnel livestreamed her protest, explaining that she had witnessed "terrifying" climate change first hand. She identified herself as from Lismore - a town devastated by two major floods earlier this year.
"There are people who are really angry right now and to those people, I understand... but we have to take a stand," she said, after a man approached and verbally abused her.
"It is for you, for your family that we do this."
New South Wales Premier Dominic Perrottet told a local radio station the protesters were "bloody idiots".
In the past year the activist group has forced stoppages at the world's biggest coal port - in Newcastle near Sydney - and Australia's biggest container port. It has also blockaded key traffic bridges.
Those demonstrations prompted the state government to pass new laws introducing tougher penalties for certain protests.
Demonstrators who disrupt traffic or prevent access on roads now face a maximum penalty of two years' jail and fines of up to A$22,000 (£12,400; $15000).
The legislation also created new offences targeting people blocking access to major facilities such as ports and railways.