Police have trapped around 800 students inside a Hong Kong university and have threatened to use live bullets on those who fail to surrender.
The anti-government protesters at the sprawling Polytechnic University remain holed up, fearful of police with water cannons, ammunition and armoured vehicles.
Officers used teargas last night in what has become one of the most prolonged and tense confrontations between police and demonstrators in more than five months of political unrest.
And police threatened to fire "rioters" with live bullets today.
The terrified students countered the volleys of teargas and rubber bullets with gasoline bombs, slingshots and bows and arrows.
Several of the demonstrators have been arrested.
But others have managed to hide under umbrellas and shields made out of debris.
Democratic lawmaker Hui Chi-fung said: "The police might not storm the campus but it seems like they are trying to catch people as they attempt to run.
"It’s not optimistic now. They might all be arrested on campus. Lawmakers and school management are trying to liaise with the police but failed."
Witnesses said students are determined not to surrender.
"Officially, they are saying people have to leave now, and even pointing out some ways to let you out. But when people try to leave that way, they contain them. It’s a set-up," Tang Siu Wa, a volunteer with the Protect the Children group, told The Guardian .
The 41-year-old added: "People getting tired but they don’t want to surrender."
A spokesman for the university's Student Union said: "Because most of the emergency relief team and first-aiders have been arrested and taken away, there are insufficient resources and personnel within campus to treat the injured.
He called the situation "a severe humanitarian crisis".
Protesters have blocked one of the city's major arteries, the Cross-Harbour Tunnel linking Hong Kong island to the Kowloon peninsula, for much of the past week.
