This cohort’s political evolution demonstrates the breadth of anger in Hong Kong. Where previous upwellings of public fury were often led by students, the authorities now face a scenario where regular office workers with stable jobs and promising careers have been loosed on a path to radicalization.

Violence has become commonplace at protests. Attacks on symbols of the state have expanded; businesses perceived as supporting the Chinese Communist Party have been vandalized. Protesters have thrown gasoline bombs at police stations and assaulted officers. Police say they have discovered crude explosives, though no one has been hurt by these so far.

Hundreds of thousands still demonstrate peacefully, despite the harder-line provocateurs in their midst. Residents shelter protesters fleeing from police operations. A recent survey by a polling center at the Chinese University of Hong Kong showed that almost half the respondents saw nothing wrong with protesters’ actions. Only 1.6 percent found attacking the police unacceptable.

As Hong Kong’s government, led by Chief Executive Carrie Lam, oversees an intensifying crackdown, experts say, more people will turn to violence to achieve their goals.

Hong Kong’s officials “and their Beijing bosses have all condemned violent protests as if the moral high ground belongs to them,” wrote Michael Chugani, a television host usually known for pro-government views.

“It doesn’t,” he continued. “The moral high ground belongs to the protesters. They were forced into using violence after Lam ignored their peaceful voice.”

A turning point

The six friends grew up understanding how large, peaceful rallies could effect change. Some of their families participated in huge marches in 2003 that forced the Hong Kong government to shelve plans to introduce sedition laws. In 2014, when thousands occupied the streets seeking direct elections in Hong Kong, their families were among the “wo, lei, fei” — the peaceful, rational and nonviolent protesters that formed the movement’s core and who opposed radical actions.

“In my heart, I knew the protests were useless in dealing with the Hong Kong government,” Samson, 32, said of the 2014 protests. He said it was becoming clear that the city’s government responded only to Beijing, rather than the people of Hong Kong. “But I continued my responsibility as a Hong Konger, and I continued to join in the protests.”

After 79 days, the street occupation was cleared, failing in its goal. The group of friends returned to their lives and careers.

Then came the call for protest on June 9 in opposition to a now-withdrawn government proposal to allow extraditions to mainland China. Organizers estimated that over a million people turned out.

When Samson returned home, he feared that it would be a repeat of 2014 — another mass rally of marching and chanting that failed to achieve anything.

“I hoped that the next time, I could do more,” he said. “Not just complete a march and that’s it.”

The next opportunity came June 12, when thousands of protesters took to the streets around the legislative complex to disrupt a debate on the extradition bill. Several of the friends took a half-day off, leaving their air-conditioned offices to deliver face masks and water to front-line protesters who built barricades to hold back riot officers.

Police responded with then-rare force, including tear gas, rubber bullets and beanbag rounds.

“It was our most angry day,” said Kelvin. “For me, that was the turning point. Immediately, it was clear that the authorities would treat us differently than 2014, and so we had to respond differently.”

It wasn’t until July 21, when suspected members of organized-crime gangs assaulted protesters at a subway station, that the friends started gearing up. Kelvin procured knee and arm pads, a half-face respirator and helmets.

Ryan, a 28-year-old legal assistant, purchased respirators along with a hiking stick and helmets.

“I thought, if that day comes again, to protect myself and my friends, I would use violence against [pro-Beijing gangsters],” he said. “If I don’t protect myself, I may get killed.”

Samson added: “I’ve thought about if I were one of the victims on July 21. If I didn’t have any gear, I would’ve been hurt and unable to protect my friends.”

Escalating action

At protests, the self-described nerds enlist the help of Steven, a 33-year-old construction worker. When masked front-line protesters dismantle metal barricades, dig out bricks and find other ways to hold back riot police, Steven is there with an array of tools, ready to provide expert help.

He buys lighter fluid and electrical oil to douse floors of subway stations. The liquids serve a dual purpose: to vandalize the subway, whose operator is seen as supporting Beijing, and to slow police officers who use the trains to get around on protest days, when the network is often closed to the public.

Steven sometimes gets frustrated with his bookish crew, whom he affectionately calls the “suit guys.”

“I don’t know if they just don’t get it or they have short memories,” he said. “But sometimes when I ask them to loosen a bolt or a screw, they’ll drill it the opposite way and make it tighter instead. They’ve screwed up a lot.”

Some in the team have developed their own niches. Kelvin, who is married, heads to the library to scour chemistry books for the best molotov cocktail recipes. When the first gasoline bombs were unleashed in July, he thought the flames were small and unimpressive. He wanted to make them more effective and share his knowledge with front-line protesters.

“Nowadays, you can see the huge flames and think, ‘Whoa, how amazing,’ ” he said, noting that “it isn’t an offensive tool to burn things, it is a barrier that allows our teammates to retreat.”

“The aim is not violence for violence’s sake, but to protect ourselves,” he said.

Hong Kong government officials and their counterparts in Beijing have condemned — in the harshest terms — the hundreds of cases of arson, vandalism and sporadic mob violence. On Oct. 24, China’s top diplomat in Hong Kong, Xie Feng, likened the violence at street protests to a “virus.”

The virus “knows no boundaries or limits. It is highly susceptible to being complicated by other viruses, such as populism, separatism and extremism, and developing into the tumor of terrorism,” Xie said.

On Monday, Lam, the Hong Kong leader said any “wishful thinking” that violence would pressure her government into satisfying protester demands was misplaced.

“Our joint priority now as a city is to end the violence and to return Hong Kong to normal as soon as possible,” she said.

‘Something exceptional is happening’

For a global financial center with a low crime rate, the path that Hong Kong is now on is highly unusual and bucks the conventional wisdom that violent protests dampen support for social movements, sociologists say.

“This is an extremely unusual case — it seems like something exceptional is happening here,” said Robb Willer, a professor of organizational behavior at Stanford University who found, in the context of white-nationalist rallies and anti-racist counterrallies, that violent protests tend to backfire.

Willer added that violent protests are likely to be more acceptable in settings where there is a “high level of support” for the cause, and where the violence from the “other side” is seen as worse.

The poll from the Chinese University of Hong Kong, conducted between Oct. 8 and Oct. 14, showed that almost 70 percent of respondents believe police have used excessive violence, compared with 40 percent who believe protesters are too violent.

“There is a much stronger concern about the police’s excessive use of force,” said Benjamin Cheung, a lecturer in the department of psychology at the University of British Columbia who analyzed the survey and its methodology. “In fact, there has been a small but significant shift in the direction of great public support for abandoning nonviolence as a tactic.”

The group of friends, and other more radical front-line protesters, say the battles are just beginning. Protesters are adopting guerrilla-style tactics, they say, in which groups carry out destruction in their own neighborhoods and quickly return home, avoiding arrest. Some have begun conditioning for battle by practicing sprints at the gym, taking up martial arts and improving their throwing accuracy.

“If you think about the psychology of the protesters engaged in this violence, we are somewhere along a continuum on the path to extremism,” said Antony Dapiran, author of a book on Hong Kong protests. “How far we go along that path, and how long it takes before we reach its horrifying ultimate destination, is the question.”