Hong Kong police on Sunday night fired tear gas into a rowdy but largely peaceful crowd of pro-democracy protesters, which seemingly ballooned and spread across the city only after the moment the tear gas was released from its shell.

Riot police launch tear gas into the crowd as thousands of protesters surround the government headquarters in Hong Kong, Sept. 28, 2014. (Wally Santana/AP Photo)

The crowds - for which there were no official numbers for the crowds, although activist groups were estimating them to be in the tens of thousands - effectively brought parts the international financial hub to virtual standstill for the second straight day Monday.

Pro-democracy protesters gather in the Admiralty region of Hong Kong, Sept. 29, 2014. (Aaron Tam/AFP/Getty Images)

The student protests and the Occupy Central movement were initially about electoral reforms. Beijing said in August that it would allow Hong Kong to elect its own leader if the candidates were pre-screened and friendly to Beijing. That did not sit well with some of the electorate.

Thousands of people block a main road in Hong Kong, Sept. 28, 2014. (Vincent Yu/AP Photo)

When the Hong Kong government and its police force decided to respond to protesters with force, some locals who did not initially support the week-long student protest or the plan to disrupt Hong Kong's financial district seemed to galvanize behind the two movements. A new movement and hashtag arose from the tear gas: the #UmbrellaRevolution, named after the accessory of choice the protesters chose to defend themselves.

A protester raises a placard that reads "Occupy Central" between riot policemen and protesters outside the government headquarters in Hong Kong, Sept. 27, 2014. (Vincent Yu/AP Photo)

In the brief, unexpected violence, moderate Hong Kong residents may see a future that resembled any other mainland Chinese city, where dissent is removed by a show of force.

More Photos: Hong Kong Democracy Protests vs. Tear Gas

'Hong Kong Exceptionalism'

Hong Kong, a self-governed southern Chinese territory, prides itself on its freedom of speech and assembly - a freedom its cousins in mainland China do not share.

There lies the heart of the issue: Call it "Hong Kong exceptionalism," or, at least, the perception of it - because, after all, Hong Kong is part of China. It was this "Hong Kong identity" that people seemed to be flooding into the streets to defend.

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When Hong Kong was handed back over to China from British colonial hands in 1997, the former colony was promised eventual "full democracy" under a "one country, two systems"-type of governance. Authorities also guaranteed the Hong Kong way of life would be preserved until at least 2047.

Despite its freedoms, full democracy and universal suffrage was something that Hong Kong never enjoyed as a British crown colony and something no Chinese citizen had on the mainland.

Seventeen years on, pro-democracy activists believe China is reneging on its promise.

Public opinion in Hong Kong is divided. Many residents remain politically conservative and opt for stability above all else.

Cantonese Worry About Mandarin-ization

Despite that, relations between Hong Kong and the mainland are at their frostiest since the 1997. Hong Kong has flourished as an international financial hub since the handover but the mostly Cantonese-speaking population is also going through an identity crisis. Their idea of "Hong Kong exceptionalism" is under threat.

Some Hong Kong residents are feeling squeezed out of opportunities by what they believe is a "Mandarin-ization" of the Hong Kong economy, where the highest wages are going to Mandarin-speakers with extensive mainland Chinese connections, creating an increasing wealth gap. They also believe wealthy business elites are pandering to the Chinese government in order to access the mainland market at the expense of everyday Hong Kong residents.

Changing Demographics

In 1984, when it was decided Hong Kong would return to China, the city of Shenzhen, which sits on Hong Kong's border with the mainland, had roughly 200,000 residents. Shenzhen is now dwarfs Hong Kong's 7.2 million residents as megacity of 15 million people.

The influx of mainland Chinese investors and tourists into Hong Kong have also raised property prices and a strain on some consumer goods.

When the Hong Kong police, held up as heroes in local films and on TV, fired tear gas at its own people, some may not have recognized the city they called home.

Riot policemen take position opposite demonstrators during a pro-democracy protest in Hong Kong, Sept. 28, 2014. (Xaume Olleros/AFP/Getty Images)

The New York Times quoted a recent university graduate Steve Lee in the thick of the tear gas saying, "Hong Kong has gone crazy. It is no longer the Hong Kong I know, or the world knows."