HONG KONG — A woman was hit in the eye during a protest. Passengers were beaten on a subway train. A student was shot in the chest with a live round — and now is being charged with rioting.
Each increase in the Hong Kong police’s use of force during the antigovernment protests has been met with greater anger from the public and more combativeness from hard-core demonstrators, which in turn have prompted more intense tactics from the police.
After four months of spiraling unrest, the question now is whether police officers can handle more escalations in violence without escalating it further themselves — or if the city’s thinly stretched force is bound to continue adding to the protests’ chaos and frenzy. The 30,000-strong Hong Kong Police Force has become a symbol of what many protesters regard as the unchecked power with which Beijing governs the semiautonomous Chinese territory.
Many recent demonstrations have ended with a sad, predictable coda in which residents of all ages come into the streets to heckle and scream at police officers. A crowd gathered earlier this week around officers who had handcuffed a dozen protesters, mostly young women, in the Wong Tai Sin area.
“Don’t you dare lay a finger on those girls!” yelled Mei Wong, a 60-year-old resident. “You won’t have a good afterlife if you do.”
In a sign of the strain on officers, two police groups have called for the Hong Kong government to impose curfews or adopt other emergency measures that they said would help the police get a better grip on the situation. Hong Kong government officials have been discussing whether the city’s leader, Carrie Lam, should invoke emergency powers to impose a ban on face masks, said Ronny Tong, a member of Mrs. Lam’s executive council, her top advisory body.
Wilkie Ng Wai-kei, chairman of the Hong Kong Police Inspectors’ Association, said in an interview that the “methods that the Hong Kong police have used in the past four months have not been effective in stopping the violent rioters.”
The police force has said that one of its officers shot Tsang Chi-kin, an 18-year-old student, in self-defense this week, and has described its officers as being under siege. On Wednesday night, protesters outraged by the shooting poured into the streets, vandalizing shops, blocking roads and throwing firebombs into a police station. Many of them put their hands on their chests to express solidarity with Mr. Tsang.
Mr. Ng said police officers have been acting with restraint. “In the past four months, the police have fired a gun at only one rioter,” he said. “If this were happening in other countries, many people would have been shot.”
On Thursday, the police said that Mr. Tsang had been charged with rioting and assaulting police officers — a development that is likely to further inflame tensions.
Hong Kong is known as being safe and orderly, a reputation that it owes in part to its large and modern police force. The city has more police officers per capita than London. It spends around 10 percent of its budget on security, and battling drugs and organized crime has remained a priority.
Most Hong Kong officers receive training in crowd control, part of the legacy of the police force’s origins as an enforcer of colonial power during the territory’s 150 years under British rule.
After a series of disturbances in the 1950s and ’60s, the police created a public order unit and instituted anti-riot training. The highly structured approach stood in contrast with the disorganized, often deadly methods that were used elsewhere, and Hong Kong officers were later invited to share their expertise in Britain.
“For dealing with riots, in fact we are the pioneers,” said Henry Ho, who joined Hong Kong’s police in 1976 and retired in 2015 as a senior superintendent. “We set an example to the world.”
The more immediate template for this year’s police response was set during the monthslong democracy protests in 2014, which featured the city’s first use of tear gas in years. After those demonstrations ended, the city bought three water cannon trucks that have since been deployed at this year’s protests.
The anti-riot division that was created during the colonial era, the Police Tactical Unit, has been a regular presence at recent street clashes. The blue berets that are normally part of the unit’s uniforms are typically swapped out these days for riot helmets, supplemented by shields.
“In normal circumstances, it is a civilian force,” said Lawrence Ka-ki Ho, a professor at the Education University of Hong Kong who studies policing. “But at the same time, if necessary, it may be turned into an armylike squad.”
Furor over the police’s crowd control methods first erupted early this summer, after officers tear-gassed and beat largely peaceful demonstrators on June 12. The authorities seemed to pull back somewhat in response, including when protesters twice surrounded police headquarters.
But the sieges of the headquarters were an important turning point for the police, said Ray Yep, a professor of political science at City University of Hong Kong. “I think they believe they have been humiliated.”
Since then, the police have stepped up the use of tear gas, rubber bullets and on-site arrests. The protesters have also become more provocative. In addition to hurling firebombs, they have attacked officers’ residences and taunted them by chanting, “The whole families of dirty police deserve to die.”
Senior police commanders say that they are working to ensure that officers act professionally despite the chaos and the pressure. But certain incidents have raised questions — including from some former officers — about whether the force can keep its people from overstepping boundaries in the heat of the moment.
The police’s use of tear gas has been criticized as indiscriminate and excessive, with canisters fired in subway stations and from perches above crowds. Tempers flared again when a senior police official suggested that a man in a yellow shirt, whom officers were accused of abusing, was in fact a “yellow object.”
Some officers at protests have been seen obscuring or not wearing identifying badges, possibly to evade scrutiny.
“When they come out, it is like hounds after rabbits,” said Clement Lai, a former police superintendent who resigned in 2015 to start a private security company. From what he has seen, some officers have seemed to be driven by an “adrenaline rush,” he said, though he added that he felt the response had been very professional over all.
Jeffery Wu, 36, served in the police during street protests against a World Trade Organization conference in 2005.
“All the tactics the police have used these past few months have violated what I learned when I was studying at the police academy,” Mr. Wu said. “In the past, the way tear gas is deployed was stringently monitored. But it seems the police are no longer controllable now.”
Police representatives have also resisted efforts to be held to account for officers’ actions, one of the main demands of the protesters. One police group expressed outrage after the city’s No. 2 official apologized for the police’s handling of a mob attack.
The force has defended its use of tear gas and said that officers had been adequately trained in the use of guns. The city’s deputy police commissioner, Tang Ping-keung, said during a news conference on Wednesday that the force was “well-prepared, confident and determined to bring Hong Kong back on the right track.”
At the same time, the government in mainland China may have deepened the divide between Hong Kong’s police and its public by vocally backing local law enforcement.
James A. Elms, 76, a retired police officer who served during the unrest of the 1960s, said that today the Hong Kong police were seen as standing for mainland China, not against it, as was the case in colonial times.
The protesters “don’t hate the cops,” he said. “They hate what they see behind the cops.”
Elaine Yu, Keith Bradsher, Elsie Chen and Ezra Cheung contributed reporting.