Police have fired tear gas to disperse protesters in chaotic scenes in Hong Kong.
Thousands of protesters descended on China's representative office in the city on Sunday evening local time in a direct challenge to authorities in Beijing, just hours after the latest protest rocked the Asian financial centre over an extradition bill.
Sunday's march focused on calls for the full withdrawal of an extradition bill, which would allow people to be extradited to mainland China for trial, and an independent investigation into complaints of police brutality.
Other demands included charges against protesters to be dropped and universal suffrage.
"I came back to Hong Kong this summer because of the protests," said Mandy Ko, 27, who is originally from Hong Kong and now lives in Australia.
"My spirit is still with Hong Kong people."
Activists formed human chains as they handed out supplies, including umbrellas, hard hats and even gas masks to protesters.
A Reuters reporter received an AirDrop message that said "Be Water", a strategy inspired by home-grown martial arts legend Bruce Lee, that encourages protesters to be flexible.
Millions have taken to the streets in the past two months in an unprecedented show of force against Hong Kong leader Carrie Lam, triggering the worst social turmoil to rock the former British colony since it returned to Chinese rule 22 years ago.
Black-clad activists, many wearing masks, defied police orders and marched beyond the official end-point of a rally that took place earlier in the day as they made their way towards the Liaison Office.
Some protesters pelted eggs at the walls of the Liaison Office, while others spray-painted graffiti.
Hundreds of riot police faced off with protesters, firing tear gas to disperse them as police and ambulance sirens echoed through the crowds.
Activists had daubed graffiti on massive concrete pillars leading up to the office, with the words "Restore Hong Kong, Revolution of Time".
Sunday's protest, which had proceeded peacefully along the police-mandated route, is the latest in a series of rallies that have plunged the Chinese-ruled city into political crisis.
More demonstrations are planned over the coming weeks, posing the greatest popular challenge to Chinese leader Xi Jinping since he took power in 2012. For Xi's Communist Party in Beijing, stability is an overwhelming priority.
Recent images of police firing rubber bullets and tear gas near the city's financial district, as well as chaotic scenes of demonstrators storming the legislature were beamed live to the world - except in mainland China, where they were blocked from many social media sites.
Earlier on Sunday, authorities used blue and white water-filled barriers to barricade government and police headquarters, while global bank HSBC, in a rare move, pulled down large metal barriers on the street level of its gleaming skyscraper building.
Most of the rallies have passed peacefully but some erupted into violence late at night as more radical protesters clashed with police.
The city's police force has come under scrutiny after officers fired rubber bullets and tear gas last month to disperse demonstrators in some of the worst violence to roil Hong Kong in decades.
Protest organisers said 430,000 people attended Sunday's rally, though police put the number at 138,000 at its peak.
The latest protest comes a day after tens of thousands gathered to voice support for the police - whom some have accused of using excessive force against activists - and demand an end to the violence.