There have been tense scenes in Hong Kong amid violent clashes between protesters and police at a university campus in the city.
Sunday had seen roads and entry points to the Polytechnic University (PolyU) blocked, as some protesters threw petrol bombs and other projectiles as they worked to lock down the site.
Police, meanwhile, threatened to use "live bullets" if anti-government protesters used lethal weapons.
According to local media, police used tear gas to block multiple efforts by protesters to leave the scene - with some people arrested as they tried to flee the area.
On Monday afternoon local time, police allowed Red Cross volunteers to enter the university to tend to injured people inside the campus.
Monday evening, meanwhile, saw thousands of people gather on the streets around the campus calling for the trapped demonstrators to be released.
Hong Kong Free Press reports that dozens of arrests have been reported over the past 24 hours.
Hundreds of people were reported to remain on campus on Monday as police continued to surround PolyU.
>600 people are still on campus with more than half of them are believed to be #polyu students, he says. dozens of them tried to leave this morning but are forced to retreat as police fired tear gas at every exit. only one of them managed to flee, according to his understanding
— Jeffie Lam (@jeffielam) November 18, 2019
Local campaigners called on the international community to support the protesters.
Prominent activist Nathan Law said police had used "endless shots of tear gas and other weapons", describing their actions as "outrageous".
In a statement, local police denied reports they had 'raided' the campus early on Monday morning.
The said: "Police continue to conduct dispersal and arrest operation. In the meantime, rioters gathering inside the Polytechnic University set fire and caused extensive damage."
Protesters stand outside of Hong Kong Polytechnic University after police gave protesters an ultimatum to leave the campus in Hong Kong, early Monday, Nov. 18, 2019. Police launched a late-night operation Sunday to try to flush about 200 protesters out of a university campus on a day of clashes in which an officer was hit in the leg with an arrow and massive barrages of tear gas and water cannons were fired. (AP Photo/Vincent Yu)In a later statement, they continued to urge anyone inside to "drop their weapons and dangerous items, remove their gas masks and leave".
In another development today, Hong Kong's high court ruled that a government law banning the wearing of masks during protests was unconstitutional.
Chief executive Carrie Lam announced the use of the emergency powers - which have not been used for more than 50 years - in October after months of street protests.
However, the South China Morning Post reports that judges today ruled the mask ban was 'incompatible' with the city's 'Basic Law'.
The major protests began in Hong Kong during the summer over a controversial extradition bill that would have allowed authorities to send suspects to mainland China.
Despite the bill having now been withdrawn, the movement soon morphed into larger pro-democracy protests - calling for free elections and an inquiry into the police handling of the demonstrations.
