Police laid siege to Hong Kong Polytechnic University on Sunday night, warning people to leave or face action for “taking part in a riot”. That came after an extremely violent day that saw the two sides battling each other around the strategically located campus in Kowloon. At 10pm, a white Ford sedan without licence plates tried to ram a group of police officers just outside the Gun Club Hill barracks on Austin Road. An officer fired one live round at the vehicle and another one shot it with a rubber bullet. The car stopped and then took off towards Tsim Sha Tsui, police said. The normally serene neighbourhood around the campus on Austin Road turned into a war zone, with masked radicals occupying PolyU waging pitched battles against riot police. A police source said dozens of people had been arrested at the campus, and hundreds of others were estimated to be inside. Mass arrests were expected. Police said that most of the dangerous materials they had seized from arrested radicals over the past few days were stolen from PolyU laboratories. The materials were highly flammable and could be used to make explosives. Police said it was one of the reasons they had to take back the occupied campus. Both sides stepped up their use of violence. The radicals shot arrows and hurled petrol bombs and bricks – sometimes from catapults mounted on the roof of campus buildings. Police fired a large quantity of tear gas and deployed two water cannons and armoured vehicles. Amid the chaos, a 39-year-old sergeant handling media liaison was injured by an arrow, which pierced the inner back of his left leg and almost came out the other side. He later received surgery to have the arrow head removed. At the time of publishing, the fighting had raged for more than 12 hours. At nightfall, the battleground shifted to the other side of the campus near the blocked Cross-Harbour Tunnel at Hung Hom. Two sides battled to gain control of a strategically located footbridge overlooking the highways to the tunnel. The footbridge also connects the Hung Hom railway station to the campus. Radical protesters first put up bricks to slow the police advance. Later they set flammable material and other debris on the footbridge ablaze, sparking a huge bonfire and causing several explosions. The whole footbridge burned uncontrollably, with dense clouds of smoke billowing from it. Blazing debris was seen falling on the highway below. Firefighters managed to put the blaze out after about 30 minutes. But the radicals soon torched another flyover that ran parallel to the footbridge and was even closer to the mouth of the tunnel. A police armoured vehicle sent to take the flyover was attacked by a rioting crowd and set on fire. The driver had to put the vehicle in reverse, rumbling away from radicals who kept pelting petrol bombs at it. It was not immediately clear if anyone was injured. Police on Sunday night issued a statement describing what happened at PolyU as a riot. “Anyone who enters or stays on the campus and assists the rioters in any way will risk committing the offence of ‘taking part in a riot’,’’ the statement said. It asked people staying on the campus to leave. Police set up checkpoints and would only allow people to leave through a designated exit. All of them, including journalists, coming from the campus had their bags searched. This caused tension between police and some reporters. The police public relations branch had warned that anyone who left the campus without press credentials would be arrested, according to the Hong Kong Journalists Association. The identity of the masked radicals remained unclear, but many were apparently outsiders who had no real connection with the university. PolyU issued a statement condemning the behaviour of those occupying the campus and urged them to leave immediately. “The PolyU campus has been occupied by activists and has been severely and extensively vandalised over the past few days. The unlawful activities and acts of violence inside the campus and in its vicinity have been escalating, including damage to a number of laboratories on campus with the dangerous chemicals inside being taken away,” it said. It called on all its teaching staff and administrators to persuade students who were still staying in the campus to leave. “We understand that our students are very concerned about the current social issues. However, in striving for one’s goal, one must always act with calmness and rationality,” it said. Sunday’s rampage was in sharp contrast with Saturday, when hundreds of volunteers and local residents came out to clear roadblocks. They managed to clear most of the roads with only some minor skirmishes with radicals. By Sunday, PolyU was the last stronghold occupied by the masked radicals following a week of escalating violence. The Cross-Harbour Tunnel linking Hong Kong Island to Kowloon had been blocked since Wednesday night – the longest forced closure in its history. Its toll booths were torched and debris strewn all over the vehicle lanes. On Sunday morning, dozens of volunteers tried to clear roadblocks on Austin Road near the northern part of the PolyU campus. But they met stiff resistance as a group of masked men hurled bricks at the unarmed volunteers. Police arrived but they were met with petrol bombs. Soon rounds of tear gas were fired and the conflict quickly escalated. In front of Rosary Church and the Gun Club Hill barracks of the People’s Liberation Army, riot police and masked protesters waged battles. Police called in two water cannon trucks and two armoured vehicles and made several attempts to breach the radicals’ defence line. Each time they were met with stiff resistance. The protesters scattered sharp spikes and bricks on the ground. From the commanding height of the campus rooftop, they thwarted the police advance with a hail of petrol bombs and projectiles. Among those on the front line of the confrontation was salon worker Tsang, 20, who pledged to stay until the bitter end – meaning police storming in and arresting him. “Of course I am worried about my safety. But we have sacrificed a lot already, with so many protesters having been arrested. We just can’t stop,” he said. “I know the risk. But I am not leaving.” Clashes have mostly been concentrated on the Kowloon side of the city, apart from the main battleground of Hung Hom around PolyU, Mong Kok and Yau Ma Tei also saw confrontations. The Hong Kong side was quieter. The University of Hong Kong issued a statement saying conditions around its main campus and Centennial campus had improved, but the damage to facilities would take some time to repair. It advised staff to work from home if possible and avoid the university. The university said it would set up identity checks at entrances and exits to all of its campuses, and at building entrances. Baptist University also put in place similar controls. The Education Bureau has announced that classes at all schools in Hong Kong would continue to be suspended on Monday. Reporting by Phila Siu, Albert Han, Jeffie Lam, Danny Lee, Lilian Cheng, Sum Lok-kei and Danny Mok Below is the message in full sent out by Polytechnic University: Dear Students, Colleagues and Alumni The PolyU campus has been occupied by activists and has been severely and extensively vandalised over the past few days. The unlawful activities and acts of violence inside the campus and in its vicinity have been escalating, including damage to a number of laboratories on campus with the dangerous chemicals inside being taken away. All classes have been forced to be suspended and all operations on the campus have been halted. The University is gravely concerned that the spiralling radical illicit activities will cause not only a tremendous safety threat on campus, but also class suspension over an indefinite period of time. Once again, we plead with all people on campus, including students and staff members, to leave immediately. We understand that our students are very concerned about the current social issues. However, in striving for one’s goal, one must always act with calmness and rationality. Using violence or other radical means will not resolve problems, and instead it will cause a breach of the peace in our society, as well as traffic disruption. PolyU is the second home for our students, teachers and alumni, who have put painstaking efforts into building it up with the generous support from the community over the past eight decades. We are all heart-broken and in deep distress to witness the severe devastation of this home. We believe that most of the alumni, staff and students of the PolyU, as well as their relatives and friends, are deeply saddened to see the campus and the nearby areas completely wrecked, the traffic disrupted, and the University indefinitely closed. They are concerned about the safety on the campus, and they do not want to see the campus being destroyed further. We sincerely urge our students to stand together with us in cherishing and guarding themselves as well as this campus that we call home. We appeal again for all to stay calm and rational and say “No” to violence. Do not engage in any violent or unlawful activities. In this moment of utmost risk, stay away from any danger and always be vigilant in protecting yourselves to relieve our, as well as your friends’ and relatives’ worries about you. We have called on Deans, Department Heads and teachers to persuade our students to leave the campus as soon as possible. We also appeal to the parents and friends of the students to make efforts in doing likewise. Universities are venues for advancing knowledge and nurturing talents. Universities are not battlegrounds for political disputes and should not be drawn into violent confrontations. PolyU strongly condemns the occupation of the campus by the people who commit acts of violence and demands that they leave immediately. In this difficult time, we again call on all parties in society to maintain calm and restraint. We also plead with the members of PolyU to stand together. With our concerted efforts, we hope the campus can return to peace and tranquillity soon, and the impasse and turbulence in the society will come to an end. Best regards, Dr LAM Tai-Fai, Council Chairman Professor Jin-Guang TENG, President Professor Philip C. H. CHAN, Deputy President and Provost Dr Miranda LOU, Executive Vice President Mr Andy TONG, Vice President (Campus Development and Facilities) Ir Professor Alex WAI, Vice President (Research Development) Ir Professor Ben YOUNG, Vice President (Student Affairs) Professor S. L. HO, Associate Vice President (Academic Support) Professor Chetwyn CHAN, Associate Vice President (Learning and Teaching) Professor Guohua CHEN, Associate Vice President (Research Support) Professor K. Y. WONG, Associate Vice President (Research Support) Professor Daniel T. L. SHEK, Associate Vice President (Undergraduate Programme) Professor WONG Wing-tak, Dean of the Faculty of Applied Science and Textiles Ir Professor T. C. Edwin CHENG, Dean of the Faculty of Business Ir Professor Y. L. XU, Dean of the Faculty of Construction and Environment Ir Professor H. C. MAN, Dean of the Faculty of Engineering Prof. David SHUM, Dean of the Faculty of Health and Social Sciences Professor LI Ping, Dean of the Faculty of Humanities Professor K. P. LEE, Dean of the School of Design Professor Kaye CHON, Dean of the School of Hotel and Tourism Management Professor Esmond MOK, Dean of Students