Hong Kong police have used pepper spray and batons to stop protesters storming parliament amid growing anger over a controversial extradition bill.
Protesters have blocked key roads around government buildings and threw bricks and projectiles at police.
The government is still pushing for the bill which would allow extradition to mainland China and it is expected to pass its final vote on 20 June.
But the Legislative Council (LegCo) has now delayed its second reading.
Up until now, protests had been largely peaceful as thousands of protesters took to the streets and attempted to block access to government buildings ahead of the scheduled debate of the bill.
But on Wednesday, the demonstrations escalated, with tear gas and beanbag rounds being fired as activists tired to storm government buildings.
The BBC's Gabriel Gatehouse is inside the LegCo building where police have effectively barricaded themselves. He reports one officer is injured and was carried away. The doors have been padlocked.
Pictures shared on social media show protesters hit by water cannon struggling to protect themselves with umbrellas, while images allegedly taken from a local TV station are showing police officers armed with rubber bullets.
"This behaviour has gone beyond the scope of peaceful gatherings," the Hong Kong Police Force said in a tweet on Wednesday.
Matthew Cheung, Hong Kong's administration chief, has urged protesters to stop occupying major roads and disperse as soon as possible, the Sing Tao Daily reports.
But one young protester, decked in a black mask and gloves, told news site AFP that they would not "leave [until] they scrap the law".
Political party the Hong Kong National Front has threatened to enter the Legislative Council and remain "indefinitely" on strike if the government does not withdraw the bill.
Critics of the bill of amendments to the extradition laws cite the alleged use of torture, arbitrary detentions and forced confessions in the Chinese judicial system.
The government has promised legally binding human rights safeguards and other measures it says should alleviate concerns.
Nevertheless, this has led to the largest rallies the territory has seen since it was handed back to China by the British in 1997.
Police said they are also investigating death threats made against Hong Kong's Chief Executive, Carrie Lam, and members of the justice department over the bill.