A Hong Kong police officer has been wounded in the leg with an arrow as
security forces and anti-government protesters engaged in renewed clashes.
Images showed the arrow embedded in the leg of the media liaison officer outside the campus of the city's Polytechnic University (PolyU).
Masked protesters armed with bows and arrows were seen patrolling the campus.
Months of often violent demonstrations have caused political and economic turmoil in Hong Kong.
Protests were triggered by a now-withdrawn plan to allow extradition to mainland China but have since expanded into wider demands for greater democracy and for investigations into the actions of police.
Protests in Hong Kong
Most recently, Hong Kong's university campuses have been the scenes of pitched battles between police and demonstrators.
On Sunday, riot police fired tear gas and used water cannon against protesters at the PolyU, who launched bricks and petrol bombs at them.
Protesters took cover behind umbrellas on a footbridge close to the nearby Cross-Harbour Tunnel and set light to debris there, causing a huge fire.
The blaze triggered a number of small explosions, witnesses said, and fire crews eventually moved in to douse the flames.
In a statement the university urged those occupying the campus to leave immediately.
"University is a place for inventing knowledge and nurturing talents. It shouldn't become a political battleground or be dragged into violence," it read.
Police said the wounded officer had been on duty near the PolyU when he was hit by the arrow on Sunday afternoon.
"Such acts are life-threatening to everyone on the scene," a statement on Facebook said.
"The force strongly condemns the violent acts of rioters and is carrying out its dispersal and arrest actions now. We call on citizens not to head towards the PolyU area as the situation is sharply deteriorating."
Why are there protests?
Hong Kong - a British colony until 1997 - is part of China under a model known as "one country, two systems".
Under this model, Hong Kong has a high degree of autonomy and people have freedoms unseen in mainland China.
The protests started in June after the government planned to pass a bill that would allow suspects to be extradited to mainland China.
Many feared this bill would undermine the city's freedoms and judicial independence.
The bill was eventually withdrawn but the protests continued, having evolved into a broader revolt against the police, and the way Hong Kong is administered by Beijing.