– Johannie Tong, detained for seven hours by the Hong Kong police for an illegal democracy protest, said more people will take to obstructing the streets if China doesn't agree to give up control over the city's election.

Hundreds of police cleared protesters from a sit-in that disrupted the city's financial district Wednesday, arresting 511 people who stayed on after a mass rally opposing China's insistence on vetting candidates for Hong Kong's 2017 leadership election. Tong, a 19-year-old student, and other activists said this is only the start of a more radical pro­democracy campaign.

The sit-in and a Tuesday march that was the city's largest in a decade showed the growing chasm between Hong Kong citizens who demand full democracy and a Chinese government that says a "patriot" must serve as chief executive. At stake is the stability that underpins Hong Kong's position as a financial center.

"If the government does not treat our demand seriously this time, I would join the demonstration a second time," Tong said after her release. The hardening resolve of young people increases pressure on Hong Kong Chief Executive Leung Chun-ying.

"The governments are very intransigent," lawmaker Emily Lau said. "They always stick to their points without any room for negotiations. If they continue to do so, Hong Kong will have to pay a heavy price, and so will Beijing."

Public unrest in Hong Kong has worsened in the past month after a Chinese policy paper spelling out tighter control of the city spurred almost 800,000 people to vote in an unofficial referendum against China's proposed limits on leadership candidates.

Protesters urged Leung and Beijing to heed their demands. While most left before midnight, thousands remained beyond the time police had permitted for the protest.

Leung's administration reiterated that public nomination of candidates, which the movement wants, is unlikely to win consent. Leung urged people in a speech not to do anything that could undermine Hong Kong's stability and prosperity.

"It seems that the governments in Beijing and Hong Kong are not going to give way," said Chung Kim-Wah, an assistant professor at the Hong Kong Polytechnic University Department of Applied Social Science. "If that's the case and with the civil referendum, it seems that the prodemocracy camp is also not going to compromise. The gap is widening."

The rights of Hong Kong's people have been protected during the 17 years of China's rule, China's Foreign Ministry spokesman Hong Lei said on Wednesday. The city's government is working on the introduction of universal suffrage in a gradual manner, he said.

"The people have made their statement very clearly," said Yvonne Leung, a student leader who helped organize Wednesday's sit-in. If the government doesn't take heed, "there will be more and more" protests, she said.