HONG KONG (Reuters) -- Hong Kong police on Monday trapped hundreds of protesters inside a major university, sealing off roads in the area after almost two straight days of standoffs that have raised fears of a bloody showdown with both sides refusing to back down.
Hundreds of defiant protesters inside Hong Kong's Polytechnic University faced off against a police water cannon and armoured vehicles in raging battles that lasted an entire day and into the night.
A police officer was shot in the calf by an arrow as anti-government protesters, many of them students, responded to police with salvos of petrol bombs and bricks hurled by homemade catapults.
Police threatened to fire live bullets if "rioters" did not stop using lethal weapons in the latest flare-up in anti-government protests that have convulsed the Chinese-ruled city for five months.
Scores of protesters were injured, some with scalding burns from chemicals in the jets fired from the water cannon.
The protesters at Polytechnic University had blocked one of Hong Kong's major highways, the Cross Harbour Tunnel linking Hong Kong island to the Kowloon peninsula for much of the past week, with authorities desperate to restore the link yet encountering tenacious resistance from the trapped activists.
Thousands of residents and protesters flocked to various districts around the university including Tsim Sha Tsui, Jordan and Yau Ma Tei, to try to penetrate the riot-police lines to rescue the trapped students.
"If we can only hold on till dawn, more might come," said one young activist in the university who was close to exhaustion.
The violence in the Asian financial hub has posed the gravest popular challenge to Chinese President Xi Jinping since he came to power in 2012. Xi has said he is confident Hong Kong's government can resolve the crisis.
In Monday's statement, police warned people whom they described as rioters to stop using lethal weapons to attack officers and to halt other acts of violence, saying officers would respond with force and possibly live bullets if necessary.
Demonstrators, angry at what they see as Chinese meddling in the former British colony that has had autonomous status since returning to Chinese rule in 1997, have said they are responding to excessive use of force by police.
"The protesters have been reacting to the police," said Joris, 23, a civil engineer who like others did not give his full name. "We haven't fought back as much as we could. I would be prepared for jail. We are fighting for Hong Kong."
Beijing denies interfering in Hong Kong's affairs and has blamed foreign influences for the unrest.
Many others trapped on the sprawling red-brick campus close to the city's harbour, said they would never surrender.
"We’ve been trapped here, that’s why we need to fight until the end. If we don’t fight, Hong Kong will be over," said Ah Lung, a 19-year-old protester.
Many protesters wore gas masks or tied handkerchiefs over their mouths and noses to protect themselves from clouds of tear gas. Some stripped down to their underwear, after earlier dousings from water cannon that witnesses said contained an irritant.
An armoured police vehicle that was set ablaze by petrol bombs in Sunday's violence was towed away early on Monday.
The spectre of a bloodier standoff has caused some international concern.
Former British Foreign Secretary Malcolm Rifkind said in a statement: "Hong Kong's Chief Executive has the responsibility to do everything possible to prevent a massacre. She must order the police to use restraint."
Several blocks from the university, black-clad protesters gathered in Nathan Road, another major thoroughfare, digging up pavement and using bricks to block roads. The demonstrators shouted: "Liberate HK, revolution of our time."
Police had said on Sunday that police had fired a bullet, but did not give details about the latest use of live ammunition. Police shot and critically wounded a protester on Nov. 11.
Chinese soldiers in a base close to the university were seen on Sunday monitoring developments with binoculars, some dressed in riot gear.
Chinese troops in shorts and T-shirts, some carrying red plastic buckets or brooms, emerged from their barracks on Saturday in a rare public appearance to help clean up debris.
The presence on the streets of soldiers from China's People's Liberation Army (PLA), even to clean up, risks stoking the controversy about Hong Kong's status as an autonomous area.
Chinese troops have appeared on Hong Kong's streets only once since 1997, to help clear up after a typhoon last year.