Hundreds of protesters were arrested as they tried to leave a Hong Kong university campus that was surrounded by police.
A group of around 100 people tried to leave Polytechnic University, but were met with tear gas and rubber bullets.
This was the third time protesters have tried to leave, following a fiery overnight stand-off with police.
The police are continuing to lay siege to the Polytechnic University where several hundred protesters are thought to be trapped. Officers have ordered those inside to drop their weapons and surrender.
In the past week, the campus has turned into a battleground as long-running anti-government protests become more violent.
PolyU has been occupied by protesters for several days. On Sunday night, police warned protesters they had until 22:00 local time to leave the campus, saying they could use live ammunition if the attacks continued.
On Sunday, the university said it had been “severely and extensively vandalised”.
A number of protesters left inside in the university have identified themselves as current students in media interviews. But it is unclear exactly how many of them are, in fact, university students.
Campuses remained relatively free of violence during the Hong Kong protests but, last week, the Chinese University of Hong Kong became a battleground.
Police said protesters threw petrol bombs on a major road near the university in an effort to stop traffic. Officers attempted to reclaim the road, leading to major clashes.
Meanwhile, in a slight win for pro-democracy protests Hong Kong’s High Court ruled that a ban on protesters wearing face masks was unconstitutional. A colonial-era emergency law was invoked in October to invoke the ban.
The violence is some of the worst seen during months of unrest in the semi-autonomous Chinese territory. The protests started over a controversial extradition bill, and have now evolved into broader anti-government demonstrations.
Chinese foreign ministry spokesman Geng Shuang said: “No-one should underestimate China’s will to safeguard its sovereignty and Hong Kong’s stability.
Hong Kong’s government said the weekend’s events had “reduced the chance” of district elections being held on Sunday as planned. However, postponing or cancelling the vote could further inflame the protests.
The UK’s Foreign Office has expressed concern, saying: “We need to see an end to the violence, and for all sides to engage in meaningful political dialogue ahead of the district council elections.”