Several protesters have been arrested while trying to run from a Hong Kong university campus surrounded by police.
Around 100 people tried to leave the Polytechnic University, but were met with tear gas and rubber bullets.
In the past week, the campus has turned into a battleground as long-running anti-government protests become more violent.
That a ban on protesters wearing faces masks was unconstitutional. The colonial-era emergency law was invoked in October, but protesters largely defied 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.
China has warned that “no-one should underestimate China’s will to safeguard its sovereignty and Hong Kong’s stability”.
