PHOTO GALLERY: Security forces crack down on Hong Kong democracy protests

Multimedia

Riot police fire teargas to disperse protesters after thousands of demonstrators blocked the main street to the financial Central district outside the government headquarters in Hong Kong September 29, 2014 (Photo: Reuters)

Riot police fire teargas to disperse protesters, after thousands of protesters blocked the main street to the financial Central district outside the government headquarters in Hong Kong September 28, 2014 (Photo: Reuters)

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

Protesters run for cover as riot police fire teargas after thousands of protesters blocked the main street to the financial Central district outside the government headquarters in Hong Kong September 28, 2014 (Photo: Reuters)

Thousands of pro-democracy demonstrators gather at Hong Kong's government headquarters Sunday, Sept. 28, 2014 (Photo: AP)

Protesters block the main street to the financial Central district, outside the government headquarters in Hong Kong, September 29, 2014 (Photo: Reuters)

Pro-democracy protesters sit on a road as they face-off with local police in Hong Kong Monday, Sept. 29, 2014 (Photo: AP)

Protesters gather at a main road at the financial central district after riot police use tear gas against them after thousands of people blocked the road in Hong Kong, Sunday, Sept. 28, 2014 (Photo: AP)

Student protesters occupy streets surrounding the government headquarters in Hong Kong, Sunday evening, Sept. 28, 2014 (Photo: AP)

Riot police fire tear gas on student protesters occupying streets surrounding the government headquarters in Hong Kong, early Monday, Sept. 29, 2014 (Photo: AP)

Riot police fire teargas to disperse protesters, during clashes after thousands of protesters blocked the main street to the financial Central district (background) outside the government headquarters in Hong Kong September 28, 2014 (Photo: Reuters)

Hong Kong police used tear gas for the first time on Sunday to disperse pro-democracy protests and baton-charged the crowd blocking a key road in the government district after Hong Kong and Chinese officials warned against illegal demonstrations.

Police had not used tear gas in Hong Kong since 2005, to break up World Trade Organization protests against South Korean farmers.