Riot police advanced on Hong Kong democracy protesters in the early hours of Monday, firing volleys of tear gas that sent some fleeing as others erected barricades to block the security forces in the heart of the former British colony.
Earlier, police baton-charged a crowd blocking a key road in the government district in defiance of official warnings that the demonstrations were illegal. Several scuffles broke out between police in helmets, gas masks and riot gear, and demonstrators angered by the tear gas, last used in Hong Kong in 2005.
The unrest is the worst since China took back control of Hong Kong from Britain in 1997. It poses a serious challenge to Communist Party leaders in Beijing, concerned that calls for democracy could spread to cities on the mainland and threaten their grip on power.
Thousands of protesters were still milling around the main Hong Kong government building, ignoring messages from student and pro-democracy leaders to retreat for fear that the police might fire rubber bullets. Police, in lines five deep in places, earlier used pepper spray against activists and shot tear gas into the air. The crowds fled several hundred yards (meters), scattering their umbrellas and hurling abuse at police they called "cowards."