Rights groups hit out at Hong Kong police on for 'fanning the flames' of violence as desperate protesters remain trapped inside the Polytechnic University (Poly U) and hundreds more waged pitched battles with riot police in Kowloon.



Amnesty International called the police siege of Poly U one of the most violent confrontations of the five-month-old protest movement, laying the blame on the police.



"By laying siege & firing tear gas & rubber bullets at people trying to flee, Hong Kong Police are again fanning flames of violence when

they should be trying to defuse it," the group said via its Twitter account.



"It is the police’s responsibility to de-escalate this situation, but instead of assisting injured protesters trapped at the University they are unlawfully arresting the medics attempting to treat the wounded," it said.



The U.S.-based group Human Rights in China also condemned police action in and around Poly U, "trapping students, journalists, and first aiders, and reportedly handcuffing the latter group."



Video footage circulating online of scenes from early morning Nov. 18, Hong Kong time, showed police chasing and grabbing students inside campus at around 5:30 a.m., as well as police firing tear gas at cars on a highway near the campus driven by citizens intending to help with evacuation; and injured students being carried out of campus at around 6:00 a.m, it said.



Jin-Guang Teng, President of Poly U, said he had negotiated a temporary cease fire with police "under the condition that if the protesters do not initiate the use of force, the police will also not initiate the use of force."



"We have also received permission from the police for you to leave the campus peacefully and I will personally accompany you to the police station, to ensure that your case will be fairly processed," Teng said.



A few hundred students and teachers are believed to be trapped in the Poly U campus.



One frontline protester apologized to his parents for taking part in the defense of the campus, saying that they had warned him never to become a frontline fighter.



"I'm sorry that I was unable to fulfill this wish," he said. "I have nothing to leave them, even though they raised me. I just hope we'll be able to sit down again for a family meal."



"I left without telling them. They don't know I'm here ."



Students don't trust the police

One worried parent told RFA they fear he will have criminal charges pinned on him by the authorities, just for being at Poly U.



"He's just a kid," the parent said. "The government has thought about what it was they did to make young people come out in protest ."



"They will avoid the issue forever, and they're not listening to the people."



Poly U student spokesman Owan Lee said the students didn't trust the police enough to leave peacefully.



"Video clips show that that there have been search-and-arrest raids carried out on campus by [special squad] raptors, which once more gives the lie to police claims that they didn't enter the campus," Lee told journalists on .



He said a number of students were injured by rubber bullets, or were suffering hypothermia after being hit by water cannon.



"Chief Executive Carrie Lam must take immediate responsibility for the crisis—a crisis created by her failure to address the concerns of millions of Hong Kong people over the past six months of protests," HRIC executive direct Sharon Hom said in a statement.



"Continuing to allow the police to conduct deadly urban warfare against the population will only further fuel public anger, more violence, and more protests," Hom said.



HRIC called on the international community to support the key demands of the protest movement, including the establishment of an independent commission to investigate reports of police abuse and violence and to monitor.



Pro-democracy lawmaker Tanya Chan said there are concerns for an unknown number of students injured after police broke through one of the barricades just before dawn.



"We know that quite a few people were injured ... and we know that none of them has received the treatment in hospital that they need," Chan said. "They are only able to get first aid from paramedics."



"We call on Carrie Lam to allow the injured to leave as soon as possible and get the attention they need," she said.



Former colonial-era second-in-command Anson Chan also called on Lam to order police--some of whom are carrying AR-15 assault rifles amid warnings that they could shoot protesters who throw bricks and Molotov cocktails at them--to stop using lethal weapons.



Joshua Wong, a former leader of the 2014 pro-democracy movement, said the responsibility for the escalating violence lay firmly with Lam and Beijing.



"HK protesters exhausted every peaceful means to persuade this ruthless gov't in last 5 months," Wong said via his Twitter account. "I recall on 1 July when desperate protesters stormed [the Legislative Council], a slogan read 'it's you taught me peaceful protests are useless'. Did #CarrieLam or #XiJinping listen to people? No.



Human chains

The U.K. foreign office said it was "seriously concerned by the escalation in violence from both the protestors and the authorities around Hong Kong university campuses."



"It is vital that those who are injured are able to receive appropriate medical treatment, and that safe passage is made available for all those who wish to leave the area," it said in a statement on its website.



Clashes raged throughout between riot police and protesters trying to approach Poly U to offer support and reinforcements, while small groups of protesters continued to make desperate bids for freedom, many of them only to end up being arrested and beaten by police.



"Officers battered some of their captives with batons and dragged some along the ground, while service revolvers were pulled out at one point," government broadcaster RTHK reported. "Some of those detained were covered in blood."



Police deployed tear gas, water cannon and rubber bullets against a crowd trying to push through towards Poly U from Jordan district, with hundreds forming human chains to pass bricks, umbrellas and other supplies to frontline fighters.



Thirty-eight people were injured overnight on , according to the Hospital Authority. However, the figure was unlikely to include people trapped inside Poly U.



Police made more than 150 arrests over the weekend, bringing the total number of arrests since the movement escalated in early June to nearly 5,000.



The United States condemned the "unjustified use of force" in Hong Kong and called on Beijing to protect Hong Kong's freedom, a senior official in President Donald Trump's administration said.



The clashes came after People's Liberation Army (PLA) troops in sports clothes were seen clearing debris from roads and barricades following the weekend's clashes. Some wore basketball shirts bearing the name of an elite anti-terrorist squad.



Chinese defense ministry spokesman Wu Qian said the clean-up campaign was welcomed by Hong Kong citizens.



The High Court on ruled a controversial ban on face masks in public was unconstitutional.



Reported by Tseng Yat-yiu, Man Hoi-tsan, Lau Siu-fung, Tseng Lap-yin, Wong Lok-to, Qiao Long and Lu Xi for RFA's Mandarin and Cantonese Services. Translated and edited by Luisetta Mudie.