With that style, Hong Kong police became known for managing large demonstrations, such as rallies to decry the Tiananmen Square crackdown in 1989 and a 2003 march to oppose a bill defining treason and sedition. The territory’s policing was so respected that Hong Kong officers trained British forces in crowd control.

Read: Hong Kong’s protests have cemented its identity

The professionalism and respect the force won helps explain why, in 2014, many Hong Kongers were stunned and outraged when police shot 87 rounds of tear gas to drive pro-democracy protesters from a central artery called Harcourt Road. Police had violated a moral compact with their fellow citizens. The tens of thousands of people who had picketed exploded into hundreds of thousands, many who occupied the highway for 79 days, as they chanted for democratic rights but also decried “black cops.”

The difference, Tsang, the professor, said, was that Hong Kong police now receive training from mainland Chinese agencies. During the 2014 Umbrella movement, participants and journalists witnessed troubling episodes. In a separate strike hub, thugs arrived and punched random protesters before the attackers were led away and freed by police. In a park one night in October, riot police hit protesters with batons as plainclothes officers pummeled and kicked the activist Ken Tsang, leaving his face unrecognizable. The seven officers were convicted of his assault, but incredibly, Tsang, too, was found guilty of assaulting police and resisting arrest, and served a brief prison term.

By the time young people gathered on a road in Mong Kok in February 2016 to usher in the Lunar New Year, officers seemed to have shelved the notion of crowd management. Riot police used their long shields to push the crowd as a commander engaged in a loudspeaker shouting match with Ray Wong, the founder of a political party that promoted Hong Kong’s independence from China. The night descended into a brawl as participants hurled bricks, trashed vehicles, and set fires.

The incident in Yuen Long last month exposed how much trust has frayed here. What might be brushed off as unfortunate or incompetent elsewhere is viewed in Hong Kong these days to be cruelly indifferent and perhaps corrupt. The attack immediately raised suspicions that law enforcement was protecting village residents and organized crime syndicates, known as triads, two groups that are deeply loyal to the government. The police have not helped themselves, either by issuing ludicrous statements in their officers’ defense.

The police’s actions are intimately tied with the political crisis. Many civil and professional groups have denounced the extradition bill, fearful that China could fabricate or dredge up past misdeeds to ensnare most anyone. Still, when protesters encircled Hong Kong’s legislative assembly on June 12, many expected tear gas, not that canisters would be fired at journalists or whizz near a lawmaker who demanded that police stop. Picketers did not anticipate being chased from a rally while choking on chemical clouds. Participants did not imagine that rubber bullets would be fired, ripping holes near eyes and inside mouths, nor were they prepared for police who pummeled participants with batons. Days later, Lam suspended the bill, yet 2 million people still marched, this time not just against the legislation, but also against the police and Lam’s continued tenure.

It’s rare now to see officers in their regular blue uniforms. They are dressed for a riot hours before young people converge on the streets. Police flags, alerting people that force will be used, were once raised repeatedly and for lengthy stretches, yet today it’s possible to never hear a warning or see a flag before tear-gas shells sail overhead. Tear gas itself is no longer a dispersal tool, but a weapon. The United Nations human-rights office has accused the Hong Kong police of defying international standards and creating “a considerable risk of death or serious injury”; the agency joined international calls for Hong Kong to set up an independent investigation into the anti-government protests.