Several hundred riot police armed with batons, shields, tear gas guns and pepper spray sealed off the Legislative Council in Hong Kong as a similar number of protesters charged their lines shortly after midnight.
Police used batons and fired pepper spray at protesters, who still managed to close off part of a nearby road. Several people on both sides appeared to be injured, and ambulances were called. Metal barriers were left twisted and torn in the clashes.
The Legislative Council is where debates will start on Wednesday to pass a new government bill that will allow suspects wanted in mainland China to be sent across the border for trial.
Earlier today, hundreds of thousands had jammed Hong Kong's streets to protest the bill in the biggest demonstration in years. Many said they feared it put the city's vaunted legal independence at risk.
The rallies - and the violence - plunge the global financial hub into a fresh political crisis, with marchers and opposition leaders demanding the bill be shelved and that the city's Beijing-backed Chief Executive Carrie Lam resign.
After seven hours of marching, organisers estimated 1,030,000 people took part, far outstripping a demonstration in 2003 when half that number hit the streets to successfully challenge government plans for tighter national security laws.
Police chiefs called for public restraint, government-funded broadcaster RTHK reported, as they mobilised more than 2,000 officers for a march that organisers expect to draw more than 500,000 people.
That would make it the biggest rally since a similar number turned out in 2003 to challenge government plans for tighter national security laws, which were later shelved.
Hundreds of thousands of people have taken to Hong Kong's streets on Sunday in a last bid to block a proposed extradition law that would allow suspects to be sent to China to face trial
Police chiefs called for public restraint, government-funded broadcaster RTHK reported, as they mobilised more than 2,000 officers for a march that organisers expect to draw more than 500,000 people
Hundreds of thousands of people took to Hong Kong's streets on Sunday in a last bid to block a proposed extradition law that would allow suspects to be sent to China to face trial
Police chiefs called for public restraint as they mobilised more than 2,000 officers for a march that organisers expect to draw more than 500,000 people
The protest is expected to challenge a 2003 rally, which was against tightening national security laws, as the largest ever seen in Hong Kong
Early indications suggested the crowds could reach several hundred thousand, with underground rail stations jammed with people trying to join the rally, which will start at 3 pm local time in Victoria Park.
Protesters who arrived early chanted 'no China extradition, no evil law' while others called for Hong Kong's Chief Executive Carrie Lam to step down.
One protester held a sign reading 'Carry off Carrie'.
Lam has tweaked the proposals but has refused to withdraw the bill, saying it is vital to plug a long-standing 'loophole'.
The crowd included young families pushing babies in prams as well as the elderly braving 32 degree Celsius heat.
Protesters who arrived early chanted 'no China extradition, no evil law' while others called for Hong Kong's Chief Executive Carrie Lam to step down
Many of the protesters carried yellow umbrellas, which were the symbol of the 2014 protests against Chinese reforms of the Hong Kong electoral system
Endless thousands of people are seen between the skyscrapers of Hong Kong during the march on Sunday
