Plumes of smoke rose over Hong Kong’s central districts as riot police used tear gas, pepper spray and batons in clashes with protesters engaged in a long-planned civil disobedience movement Sunday to push for universal suffrage and various democratic changes — what experts are calling the largest such protest in China since Tiananmen Square.

UC Berkeley students from Hong Kong watched the events unfold at home with concern as the protests quickly escalated. On Sunday morning, organizers of the city’s pro-democracy movement “Occupy Central” announced the early start of a civil disobedience campaign to occupy the city’s business district, which was originally set to begin Wednesday on China’s National Day. Protesters aim to pressure the Beijing government to withdraw a controversial election plan as well as relaunch an electoral reform process.

“The atmosphere is intense,” said Alan Cheng, a UC Berkeley alumnus who is from Hong Kong and currently works in the city. “On one hand, it’s intense because the government is not listening to the people — on the other hand (because of the protest’s) largest scale. Even in the middle of the day, there are no cars on the road. People are entirely on the street.”

The catalyst to the protest was a decision by the Chinese government Aug. 31 allowing direct elections for Hong Kong’s chief executive in 2017 but requiring candidates to be prescreened by a pro-Beijing committee. The decision comes in the wake of various universal-suffrage issue protests in recent months by both pro-democracy and pro-Beijing groups.

The protest follows a weeklong student boycott of classes that began Sept. 22 and culminated at the government headquarters over the weekend, where thousands of students took part in a sit-in that ended in violent confrontations with police. The use of pepper spray and what many view as heavy-handed treatment of students sparked public fury, leading thousands of people to take to the streets. With demonstrations escalating into Sunday night, police fired tear gas for the first time in nearly a decade to disperse the crowd in an unprecedented display of force.

At UC Berkeley, many students from Hong Kong are shaken by the turn of events.

“Most of the people are teenagers … They have no power and no force, and there is no reason (the police) should use tear gas and pepper spray,” said Henry Kwok, a UC Berkeley junior from Hong Kong.

A supporter of universal suffrage and public nomination, Kwok argues that requiring candidates for the city’s top job to be preapproved by Beijing is undemocratic and will result in the election of a chief executive who places the mainland’s priorities above those of the Hong Kong people.

“That chief executive most likely has to follow every procedure, every order, by Beijing, which means that Hong Kong will lose its core value of freedom,” Kwok said, adding that Hong Kong people want to choose their own leader “rather than have someone nominate a leader for them.”

Since Hong Kong was handed back to China in 1997 after more than a century of British rule, it has had extensive legal freedoms, including freedom of speech and assembly, in comparison to other Chinese cities. These freedoms are the result of a 1984 joint declaration between China and Britain that guaranteed the former colony a “high degree of autonomy” in its affairs except in foreign and defense for 50 years after the handover.

Hong Kong is the first special administrative region of China, which means the city is a semi-autonomous region controlled by China, yet remains distinct from the mainland. The city’s de facto constitution states that Hong Kong will be governed under the principle “one country, two systems,” allowing it to retain its capitalist economic system and partially democratic political system.

Yet in June, China released a controversial white paper reinterpreting the document, stating that it has “complete jurisdiction” over Hong Kong and its autonomy.

According to Rachel Stern, a campus assistant professor of law and political science who researched Hong Kong social movements and Chinese politics, the current protest is significant because it harkens back to the Tiananmen Square massacre in 1989, which effectively ended large-scale democratic protests in China.

“I’ve been totally riveted by what’s happening in Hong Kong,” Stern said, adding that, in general, the world has been “pleasantly surprised” by the amount of freedom given to Hong Kong since 1997. “The furor is that (Occupy Central) might be a turning point after the handover.”

Both China and Hong Kong’s Chief Executive Leung Chun-ying condemned the protests as illegal.

Opponents of Occupy Central say that public nomination of the city’s leader violates the constitution and that people should instead focus on making the nominating committee more representative of the people of Hong Kong. Those opposed are also concerned that the protests will render the city financially and socially unstable by disrupting Hong Kong’s economy, emergency services and more.

“In the end, you’re blocking Hong Kong, so Hong Kong-ers are suffering,” said Edward Yang, a UC Berkeley senior who lived in China most of his life and disagrees with the movement’s methods. “I don’t feel like their voices are heard, especially by the important decision makers.”

According to Stern, there is room for compromise between protesters and authorities. Yet discussion is difficult not only because Beijing may be unwilling to negotiate but also because the movement itself is fragmented by various groups. There is also a possibility that Beijing may crackdown on protesters, she said.

“The scenario I’m afraid of is where there’s a crack down on the political freedom that Hong Kong enjoys,” Stern said.

UC Berkeley Chinese lecturer Weisi Cai, who is from Beijing, is not optimistic about the movement’s outcome, saying that the Chinese government is ultimately more powerful. Despite this, she hopes the protesters’ actions can help influence people in the mainland, who she said are not satisfied with their current rights but have no way to voice their opinions.

“If Hong Kong won the game — if Chinese people see Hong Kong people win the game, they may change the relationship between the people and the government in China,” Cai said, adding that she did not see any mention of the protests on Chinese social media.

To demonstrate solidarity with Hong Kong protesters, students from Harvard University launched a now-global campaign to urge supporters to wear yellow Wednesday. With students from more than 30 U.S. colleges, including UC Berkeley, reportedly participating, the campaign has garnered more than 26,000 attendees on Facebook.

A group of UC Berkeley students from Hong Kong will set up a table Wednesday near Sather Gate handing out yellow ribbons — the symbol of solidarity with Hong Kong protesters — and fliers to raise awareness.

“If I don’t stand up today, I’m not sure if I can have the chance to step up tomorrow or next year,” said Kelly Chiu, a UC Berkeley senior from Hong Kong. “Yesterday, it was actually peaceful … (but) people say it’s always peaceful before thunderstorms, and I’m afraid.”