HONG KONG—Four months into a citywide uprising, Hong Kong residents have become extremely mindful about leaving digital trails that are sent back to mainland China. Some have zapped WeChat out of their phones. Others have abandoned e-wallets developed by Chinese conglomerates like Alibaba and Tencent. They disable location tracking on their smartphones.

Protesters resist visual surveillance and facial recognition by using formations of open umbrellas aimed at cameras and helicopters. In August, some sawed down 20 “smart” lampposts in the city that they believed contained hardware for surveillance technology.

Hongkongers who do need to cross the border into Shenzhen for work use burner phones, though many have simply stopped entering mainland China. As protests take place in various districts in the city every few days, anonymity has become a matter of paramount importance.

Adopting some elements of black bloc tactics, the city’s blackshirt protesters dress identically—black shirt, black pants, black shoes, gas mask, hard hat. Some clutch umbrellas. Many have saline solution to rinse out eyes when tear gas or pepper spray hits. A rare few have power packs and functioning display screens on their backs. Uniform dress is meant to inspire kinship, but more importantly to make it difficult to identify individuals who participate in street clashes or acts of destruction.

On Friday, Hong Kong’s chief executive Carrie Lam invoked a colonial-era law to give herself emergency powers. Her first edict was to ban face masks, which protesters use to obscure their faces as well as prevent inhalation of tear gas fired by police—now a weekly occurrence across the city. Obscuring one’s face in public will carry a jail term of one year and a fine of HKD 25,000 ($3,190).

At a press conference, Lam claimed she was not, in fact, declaring a state of emergency. She said, “We must prevent Hong Kong and prevent students from taking things into their own hands, and recover Hong Kong’s future.”

Younger protesters hit the streets every weekend precisely because they have their eyes on the future. If things progress as they have been, with the Chinese Communist Party’s influence seeping into every facet of the city gradually, over years, Hongkongers believe their freedoms—of assembly, of speech, of expression, of the press, and more—will be stripped away.

Lam’s ban on face masks will apply to all public gatherings. A pro-establishment lawmaker, Michael Tien, who refused to endorse Lam’s move, said, “Now it’s all stick and no carrot.” Tien had been urging Lam’s administration to offer some concessions to Hongkongers, first by launching an inquiry into the police’s use of force.

Another lawmaker, Tanya Chan, who leads the pan-democratic bloc, said the mask ban is an excuse for Lam to invoke other emergency powers. These include authorizing arrests, shutting down telecommunications, censoring media, seizing property, and changing or enacting laws if the city falls into an emergency state.

Beyond the mask ban, pro-Beijing legislators in the city have toyed with the idea of pushing for a curfew.

Presciently, in 2016, Edward Leung, a jailed activist whose slogan “liberate Hong Kong, revolution of our time” has become a rallying cry for Hongkongers in the past four months, pointed out that shortly after Ukraine passed legislation banning masks in 2014, the Euromaidan Revolution broke out.

As word spread that Lam’s law will go into effect at midnight, thousands of people left work during lunch time in the central business district—not far from the government headquarters—to clog the streets. They chanted, “Hongkongers, resist!” A few had gas masks with them, but most wore simple surgical masks—in black, to match the color adopted by the protesters who face off with riot police every weekend. Buses, trucks, and cars blocked roads. By nightfall, when subway staff attempted to shutter a station’s exit, protesters—younger ones in gas masks and hard hats—pushed the roller gate back up and smashed its controls.

By nightfall, students still in their school uniforms had formed human chains to pass supplies to hundreds of frontline protesters who had congregated near government buildings. Crowds continued to gather in neighborhoods across the city, with activists and frontline protesters and Hongkongers still in their attire from a day at the office jamming roads together.

Branches of banks from mainland China were set on fire. Some businesses owned by pro-Beijing tycoons were ransacked, though no looting took place. The city’s subway system was shut down completely—the first time since protests broke out in June. At least three stations were flooded, while some others had their exits swallowed by flames.

If Lam thought a ban on masks would make people stay home, then she severely miscalculated. The day’s escalation and damage were spontaneous and loaded with fury, beginning with office workers amassing in the afternoon, with people from all walks of life joining in throughout the day.

A little past 11 p.m., one person boosted an excavator and drove it toward a police station, operating it based on an instruction manual that was downloaded from the internet. On live television, in several neighborhoods, some protesters read aloud a prepared statement that declares the establishment of a provisional government for Hong Kong, quoting the Declaration of Independence.

As Carrie Lam promised, the law kicked in at midnight despite a frantic judicial review aimed at temporarily suspending the ban on masks. By then, most protesters had dispersed.

The uprising in Hong Kong has shifted from anger directed at local officials like Lam to a broader insurrection against the Chinese Communist Party. On Oct. 1, when the People’s Republic of China turned 70, a large portrait of Chinese president Xi Jinping was egged for an afternoon by Hongkongers. Captions on printouts of his face read “demon” or “devil.” A black banner hung on a footbridge read that Hong Kong stands in solidarity with Tibet and Xinjiang, where an estimated 1.5 million Uyghurs are held in concentration camps. Hongkongers look at the CCP and say it is an organization of “Chinazis.” Graffiti here and there read, in Cantonese, “Congratu-fucking-lations” and “We’re celebrating the last National Day.”

It is the 118th consecutive day of protests in Hong Kong. People have adopted dark humor as they make sense of a new reality for the city. Some said Halloween starts tomorrow. Others joked that everyone now has the flu. (In Hong Kong, as well as some other locations in East Asia, it is common for those with flu-like symptoms to don surgical masks in public.)

Speaking in Beijing, the spokesman for the State Council’s Hong Kong and Macau Affairs Office, Yang Guang, said the “chaotic situation in Hong Kong cannot continue indefinitely.” Yang also insisted that the blackshirt movement is the consequence of foreign powers intervening in Hong Kong—a consistent point of disinformation pushed by the CCP.

“We’re already ‘rioters,’” one frontline protester told me Friday, invoking a word that Carrie Lam, the police, Hong Kong’s pro-Beijing officials, and the CCP use to describe those who hit the streets. “That’s 10 years in prison. What’s another year for wearing our gas masks?”