Police in Hong Kong has fired rubber bullets and tear gas in an attempt to pin back anti-government demonstrators fleeing a besieged university campus where hundreds were holed up with petrol bombs and other homemade weapons amid fears of a bloody crackdown.

After chaotic scenes overnight and a pre-dawn attempt by police to storm the Polytechnic University, police On Monday afternoon broke through the barricades of the campus to arrest those cornered inside.

Earlier, dozens had tried to escape from the university after a night of mayhem in the semi-autonomous Chinese city in which roads were blocked, a bridge was set on fire and a police officer was shot with a bow and arrow.

Many protesters, dressed in regular clothes and without gas masks, made a run for it, dodging tear gas canisters and sponge grenades, only to be forced back inside.

Some were arrested, tackled to the ground, while others scrambled and tripped over barricades and fences as police pointed guns at them and threw punches. Some were pulled back into the campus by other protesters.

Police said they fired three live rounds when “rioters” attacked two officers who were attempting to arrest a woman. No one was wounded and the woman escaped amid a dramatic escalation of the unrest that has plunged Hong Kong into chaos for more than five months.

Demonstrators are angry at what they see as China’s meddling in the freedoms promised to Hong Kong when it returned to Chinese rule in 1997. They say they are responding to excessive use of force by police.