Hong Kong police surround university where hundreds of protesters trapped

Police in riot gear move through a cloud of smoke as they detain a protester at the Hong Kong Polytechnic University. (Ng Han Guan/Associated Press)

Protesters run for cover after riot police fired tear gas toward the footbridge they were climbing down to escape from the Hong Kong Polytechnic University campus. (Anthony Wallace / AFP / Getty Images)

A protester barricaded at the Hong Kong university prepares to shoot an arrow. (Anthony Wallace / AFP /Getty Images)

A pro-democracy protester uses binoculars during a march toward Hong Kong Polytechnic University in Hong Kong. (Fazry Ismail/EPA/REX/Shutterstock)

Protesters react as police fire tear gas in Hong Kong. As night fell Monday, police tightened a siege at the school where hundreds of anti-government protesters were trapped. (Vincent Yu / Associated Press)

Protesters climb over a bridge railing to a roadway below to escape police. (Ye Aung Thu / AFP / Getty Images)

Protesters use a rope to lower themselves from the pedestrian bridge to waiting motorbikes at Hong Kong Polytechnic University. (Kin Cheung / Associated Press)

A bystander affected by tear has his eyes rinsed amid clashes between police and pro-democracy protesters in the Jordan district of Hong Kong. (Migeul Candela/EPA-EFE/REX)

Police arrest anti-government protesters at Hong Kong Polytechnic University. (Laurel Chor / Getty Images)

Police fire tear gas toward anti-government protesters trapped inside a Hong Kong campus. (Vincent Yu / Associated Press)

Pro-democracy protesters react as police fire tear gas during Monday’s clashes. (Fazry Ismail/EPA/REX/Shutterstock)

A riot police officer stomps on an umbrella used by pro-democracy protesters. (Fazry Ismail/EPA/REX/Shutterstock)