Protests in Hong Kong against alleged police violence descended into more chaotic clashes Sunday night as police fired tear gas and rubber bullets to disperse angry, black-clad demonstrators hurling bricks, umbrellas and glass bottles at officers, while elsewhere in the city a mob apparently targeting protesters attacked dozens of passengers at a subway station.

Masked demonstrators, many covered up with plastic cling wrap and other protective gear, yelled chants of “Hong Kong police: You know the law, you broke the law!” as they advanced against retreating police lines around 10 p.m. local time in a downtown neighborhood called Sheung Wan.

Hong Kong Police said on Twitter that they advanced to clear the area because the Central Police Station “was under attack,” as protesters threw bricks and “petrol bombs” at officers. Several pro-democratic lawmakers, who support the protests, initially positioned themselves between police and demonstrators to try and de-escalate the situation. Following a tense standoff, police fired several rounds of tear gas toward the crowd and were met with more fury. Local media reported that police fired rubber bullets, though it is unclear how many were injured.

Meanwhile in an area called Yuen Long, police were accused of responding too slowly as protesters came under attack by groups of men in white shirts with wooden sticks and other weapons. Lawmaker Lam Cheuk-ting and several local journalists were among those injured. Videos shared on social media showed chaotic scenes unfolding in a train station, where members of the mob at one point were seen cornering people on a train and beating them. The violence at Yuen Long marked an unprecedented escalation as the organized mob wreaked indiscriminate havoc in what appears to have been a complete absence of authorities.

Organizers say hundreds of thousands withstood sweltering heat to join in the seventh consecutive week of mass demonstrations that have plunged the city into a political crisis and galvanized resistance to Beijing’s growing influence in the China-ruled territory. The demonstrations have been largely peaceful, but have fallen into a pattern of descending into violence after assembly permits expire and protesters stay behind against police warnings.

Since early June, organizers say millions have marched in the series of demonstrations against a now-suspended bill that would have allowed extradition to mainland China. The city’s embattled leader Carrie Lam declared the bill “dead” but has not officially withdrawn it, and the movement has snowballed to demand more democratic freedoms as anger toward her Beijing-backed government spilled out into the open and united large swaths of society.

Sunday’s march, organized by the Civil Human Rights Front, demanded that the government fully withdraw the bill, retract its characterization of recent protests as a “riot,” ensure accountability for alleged instances of police violence toward protesters, and grant citizens the right to freely elect the city’s leadership. CHRF estimates 430,000 people attended; the group’s estimates regularly conflict with much lower police figures.

“In the whole world, it is only our government that thinks these protesters are rioters,” Jimmy Sham, co-convener of CHRF, said in a speech at the start of the march before crowds erupted in chants of “Democracy now!” and “Free Hong Kong!” Anger at times focused on Lam, the chief executive, with Sham denouncing her as a “pathological liar” and some demonstrators hoisting signs decrying her “tyranny.”

The former British colony was returned to Chinese rule in 1997 under an agreement called “one country, two systems,” which guaranteed 50 years of political autonomy in the economically liberal financial hub. But critics of the unelected government say Beijing is steadily chipping away their freedoms and reneging on its promise of universal suffrage.

The so-called “leaderless” protests have been overwhelmingly peaceful and mostly comprised of young activists mobilized online, though sporadic clashes have occurred between police in riot gear and small groups of more radical demonstrators. Police have on several instances deployed tear gas, pepper spray and other crowd control measures to disperse them, sometimes resulting in injuries.

Read more: Meet Legislator Roy Kwong, the ‘God’ of Hong Kong Protests

“We really need an investigation headed by an impartial judge in order for us to move forward,” says Sammy, a research assistant at a university who declined to use his last name because of security concerns. Protesters say an existing police investigative mechanism cannot be trusted to ensure accountability, but Lam has said she will not establish an independent inquiry.

On Friday, more than 30 high-profile civil society leaders, former government officials and others signed a statement urging Lam to launch such a probe in the interest of reconciliation. “The chief executive should show her political and moral courage to resolve the ongoing conflicts in society,” the statement read. “Political problems have to be resolved by political means. The government should not put frontline police officers near flashpoints of political conflicts.”

Hong Kong police, once dubbed “Asia’s finest,” have come under intense criticism since June 12, when tear gas, pepper spray and bean bag rounds were used to disperse tens of thousands of demonstrators who had amassed near the government headquarters. More than 80 people were injured during the melee, and groups including Amnesty International accused the police of using “excessive force.”

Read more: How Hong Kong’s Fight for Freedom Is a Global Battle

Pockets of violence have since been reported at several events. A massive rally on July 1, the anniversary of the territory’s “handover” to China, culminated with the storming of the Legislative Council as a small group of mostly masked, black-clad activists — now the de facto uniform of the movement — smashed through glass walls with a battering ram and ransacked parts of the building. (The intruders did, however, leave cash in exchange for soft drinks plundered from the building’s pantry.)

Last Sunday, demonstrators took their fight to the residential neighborhood of Sha Tin, a popular destination for mainland Chinese shoppers. Police corralled protesters — many of whom were reportedly already leaving — inside a shopping mall where they then deployed pepper spray, engaging in physical confrontations with several young activists. Local media outlets reported that at least 28 were hospitalized and 37 arrests were made as a result of the flare-up.

Clashes between police and protesters have eroded public trust in the city’s law enforcement. Police presence was relatively subdued for most of the day despite heightened security concerns after authorities discovered a huge cache of explosive materials in a warehouse possibly linked to a pro-independence activist. Three suspects are in custody and a motive is still being investigated, according to CNN.

Police initially asked organizers of the Sunday rally to cut it short half-way through their proposed route, but later ceded way to the massive crowds. Water-filled barriers were moved out of the way and decorated by passing protesters with messages scrawled on Post-It notes. The colorful collages of neatly penned Cantonese memos have become iconic of the movement. So-called “Lennon walls,” named after a key site in the 2014 protests known as the Umbrella Movement, have sprung up throughout the city like miniature pop-up galleries on walls, street signs, and overpasses — even on demonstrators’ bodies.

By 5 p.m. local time police had already begun urging demonstrators to leave the central district of Admiralty, where the main march ended and many began milling around near government buildings. Some resumed marching toward China’s liaison office, seen as an emblem of Beijing’s encroachment and a frequent target of protests. A few protesters, their identities hidden behind open umbrellas, vandalized the front of the building with graffiti; others hurled eggs at its facade.

The Hong Kong government issued a statement strongly condemning “protesters who blatantly challenged the national sovereignty” of China by defacing the building and the national insignia. The statement said authorities “will deal with these acts in a serious manner in accordance with the law,” and expressed concern that “a small number of radicals” were inciting the masses to commit violent acts.

Steve Lee, a 27-year-old architect, says there are differing views on where the movement will go from here. “Many people say we need to escalate actions, but actually I disagree,” he tells TIME. “I’m hopeful that coming out and showing up every weekend will eventually result in change.”

— With reporting by Abhishyant Kidangoor and Kamakshi Ayyar / Hong Kong

Write to Hillary Leung at hillary.leung@time.com.