Five months into a pro-democracy protest movement in Hong Kong, some of the most violent clashes so far took place this past weekend, as riot police stormed the campus of a university where protesters had barricaded themselves. Hundreds of demonstrators had occupied Hong Kong Polytechnic University and prepared for a siege. Later, as some attempted to leave the campus, they found themselves trapped by police cordons and tear gas. Last night, police moved in with more tear gas, water cannons, and batons after days of confrontations in and around the campus, arresting many as they attempted to flee. The protests began as a reaction to a controversial extradition bill, but have evolved into broader demands for democracy and investigations into police brutality, challenging Beijing’s authority.