HONG KONG — Lining up his camera's viewfinder as he documented a protest related to the coronavirus outbreak, Oscar Chan noticed a police officer pointing a canister right back at him. The pepper spray blasted the student journalist in the face as he clicked the shutter.

Three officers surrounded him as he tried to wash his eye, Chan said, as their colleague demanded his arrest. They affixed plastic cuffs so tightly they left scratches and bruises before charging him with theft for possessing a transit card that provides discounts for the elderly.

“They kept calling me a ‘black journalist,’ ” said Chan, 24, a term that implied he was posing as a reporter. The officer who had sprayed him berated him with homophobic slurs and threatened to rape him, he said.

Hong Kong police have arrested thousands over the course of months of pro-democracy demonstrations with many protesters facing years in prison. (Megumi Lim/The Washington Post)

After widespread unrest in 2019, dissent in Hong Kong is evolving in the coronavirus era. With the risk of infection deterring large-scale rallies, at least temporarily, protests now involve localized, spontaneous flare-ups or strikes.

But a lack of faith in authorities’ response to the epidemic has deepened anti-government sentiment; leader Carrie Lam’s satisfaction rating is at a record low, according to the Hong Kong Public Opinion Research Institute.

At the Feb. 8 protest Chan documented, some were commemorating a student’s death following a police operation, while others were protesting government plans to establish quarantine facilities for coronavirus patients in their neighborhood. Slogans of “five demands, not one less” — the refrain of Hong Kong’s democracy movement — mixed with calls for a “revolution against the virus.”

Confronted with this form of unrest, Hong Kong’s police, now clad in surgical masks, are deploying the same response: mass arrests. Of the more than 7,300 people arrested since June, one-tenth were detained this year, despite the smaller scale and frequency of protests. Among them are student journalists, civil rights observers, elected officials and medics.

On Friday, police arrested Jimmy Lai, a media tycoon known for his criticism of the Chinese government, on charges of unlawful assembly related to a protest in August. And on Saturday, violent protests flared again, the most serious clashes between police and protesters in weeks, leading to the arrest of 121 people.

Police say they are empowered to apprehend any person if there’s reason to believe they have committed a crime. In a statement to the legislature last week, police added that officers will “always strive to protect the privacy and rights of detained persons.” The force did not respond to questions from The Washington Post about mass arrests and treatment of detainees.

The wave of arrests during a public health crisis is compounding mistrust between Hong Kong residents and the city’s leaders, who are not directly elected and are widely perceived as serving the interests of the Chinese Communist Party before the Hong Kong people. As prosecutors prepare to bring hundreds to trial on riot charges stemming from the pro-democracy rebellion, the tactics are setting up a new flash point.

Arrests “are what Beijing and the Hong Kong government thinks may work, [and so] they keep on this hard-line approach,” said Eric Cheung, a legal scholar at the University of Hong Kong. “The assessment is that, in the end, there would only be a limited number of people who are prepared to risk their liberty and life to fight and protest.”

“They may be right in that sense,” he added, “but it doesn’t address the root problems — and so one day, there will be another round.”

On Feb. 8, protests flared in several districts as residents fearful of coronavirus infection pushed back against officials’ plans to set up quarantine facilities. Tactics demonstrators honed last year — road barricades, molotov cocktails, vandalism — were now employed toward a different goal.

In a statement on Twitter, police said protesters in the Tseung Kwan O neighborhood had “blocked roads with barricades, damaged traffic lights, dug up bricks on the sidewalk and threw them on the thoroughfare.” Police arrested 119 people, including Chan, another reporter and five lower-level elected officials. “We appeal to members of the public not to break the law,” police said.

Ben Chung, head of the local district council, and other elected officials arrived at an apartment block that night after hearing from an anxious resident whose daughter had been arrested.

“It is my duty to be at the scene. District councilors are responsible for their district, and we were there to see if the police were carrying out their duties properly,” Chung said.

Within an hour, police were rounding up everyone present. Chung and his colleagues were detained, he said, along with others, including a social worker and a tourist from mainland China. They were kept overnight on charges of participating in an unlawful assembly and released on bail.

“As elected officials, we were simply trying to liaise with the public and the police, and to minimize confrontation and clashes, but it seems the police don’t understand that,” he said.

Before the coronavirus outbreak, Chinese leaders urged Hong Kong to crack down on the pro-democracy protests, branding them a threat to the “one country, two systems” framework that gives the territory partial autonomy. In February, Beijing replaced its top official in Hong Kong with a hard-liner known for suppressing Christian churches in Zhejiang province.

Lawyers and legal scholars say Hong Kong’s police, in seeking to bolster weak cases in court, are resorting to extrajudicial evidence-gathering tactics.

Joe Chan, a barrister who is among a group of pro-bono lawyers representing arrested protesters, said clients have complained that police forced them to hand over phone passcodes — a process that requires a court warrant under Hong Kong law.

Clients, he said, have been asked by police to pose for evidentiary photos while wearing full-face respirators, helmets and masks, even if those items did not belong to them — potentially to implicate a person as having participated in a protest.

"There is no legal basis for the police to ask them to do such things," Chan said. "We have complained in open court [about this practice] a few times."

Others complain, too, that police have widened their dragnet to arrest not only violent protesters but human rights observers, journalists, medics and others, in contravention of international standards. Last month, 24 human rights organizations including Amnesty International wrote to Lam, imploring authorities to cease investigations into human rights observers arrested in recent months.

“Obviously, they’ve changed their strategy,” Icarus Wong, founder of Civil Rights Observer, said of the police, who detained three of his monitors Jan. 1. “They’ve made it very clear that they don’t consider anyone who is at a protest to be innocent of wrongdoing.”

Other protesters and civil observers said the strategy of mass arrests had made them less willing to take to the streets.

“It is like a yellow card in a football match,” said Chung, the district councilor. “It almost feels like these arrests are preemptive, to make you behave yourself and stop you from coming out again.”

Chan, the student journalist, has grown tired of documenting clashes and is seeking other ways to support pro-democracy causes.

“Even if I want to reject the idea, and pretend that I am not scared after my arrest, the simple truth is that [the police strategy] really works,” he said.

Tiffany Liang contributed to this report.