HONG KONG (AP) -- University students from mainland China are fleeing Hong Kong, and classes in primary and secondary schools have been suspended as clashes turn increasingly violent in the city's 5-month-long anti-government unrest.
Marine police used a boat Wednesday to help a group of mainland students leave the Chinese University of Hong Kong, which remained barricaded by demonstrators after violent clashes with police on Tuesday.
The Technical University of Denmark urged 36 students in Hong Kong to return home, saying "some of our students have been forced to move from their dormitories because they were put on fire."
The protests have taken on a strong anti-China bent, with radical demonstrators trashing branches of mainland banks, China's official Xinhua News Agency and restaurant chains whose owners support the Beijing government.
Hong Kong is part of China but has its own legal system and greater freedoms than the mainland. The protesters say those freedoms are under threat from a city government that is beholden to Beijing. China says the protesters are rioters who want to break away from Chinese rule.
For the third day in a row, protesters caused major train service disruptions, blocked streets and rallied in the central business district. They hunkered down for expected clashes with police at university campuses.
Mainland students have said in online posts that they are being targeted by protesters who have broken into their dormitories, spray-painted insults on walls and banged on their doors, the Beijing Evening News reported.
Many are taking advantage of a program that offers a week of free accommodation in one of a dozen hotels and hostels in the neighboring mainland city of Shenzhen, Chinese media reported.
The "Grads Home" service was established in 2013 to provide short-term accommodations for recent graduates looking for jobs in the tech hub.
Many subway and rail stations were closed after protesters threw debris on tracks and vandalized train cars. University classes remained suspended.
Hong Kong Baptist University told students that instruction and exams would be conducted online for the two remaining weeks of the semester, with arrangements for students who have returned to the mainland to join in.
The Education Bureau said initially that parents could decide whether to keep their children at home, then later announced that classes at primary and secondary schools would be suspended Thursday for safety reasons.
Describing the situation as outrageous, the bureau said students should stay at home "and must not participate in any unlawful activities."
Many of the masked protesters are thought to be high school and university students.
Police subdued a few protesters as a crowd gathered for a third straight day in a central business and high-end retail district, public broadcaster RTHK reported. Protesters and police remained in the area, and office workers watched from the sidewalks.
At the Chinese University of Hong Kong, students and others readied for another possible clash with police. Gasoline bombs and fires lit up parts of the campus Tuesday night, as police battled back with tear gas and rubber bullets.
Police said that over the course of Tuesday, police fired 1,567 tear gas canisters, 1,312 rubber bullets and 380 beanbag rounds. A total of 142 people were arrested and 10 people were taken to hospitals with injuries.
Security Secretary John Lee said the use of force at Chinese University was needed because protesters were dropping objects onto a roadway below.
"The police have a duty to ensure that this public safety is maintained," he told reporters. "That is why they had to ensure that they would take charge of this bridge, which previously was occupied by the mobsters."
Groups of riot police were deployed around central Hong Kong and its outlying territories to try to contain new violence. Many students at Chinese University on the outskirts of the sprawling metropolis were armed with gasoline bombs while some carried bows and arrows.
"We are afraid the police will come to attack our home and our school, and we have to protect our home and our school," said one student, who gave his name as X Chan.
The university's student union president, Jacky So, appealed for an injunction from the High Court to ban police from entering the campus without a warrant or the school's approval. Police raided the campus and fired tear gas and used a water cannon late Tuesday.
The injunction would also block police from using crowd control weapons, such as tear gas and rubber bullets, at the university. A decision was expected late Wednesday.
The city's religious leaders appealed Wednesday for an end to the violence and called on both police and protesters to show restraint.
"At this very critical point, the people of Hong Kong must unite and say no to violence," the leaders of Hong Kong's six major religious groups said in a statement.
The Chinese government's liaison office in Hong Kong said the semi-autonomous territory is "slipping into the abyss of terrorism." It called the setting of a man on fire an act of "flagrant terrorism."
On Monday, a police officer drew his gun during a struggle with protesters, shooting one in the abdomen. In another neighborhood, a 57-year-old man who was defending China was set on fire after an apparent argument.
The man remained in critical condition Wednesday, and the protester was in serious condition, the Hospital Authority said.
Chinese foreign ministry spokesman Geng Shuang said members of the U.S. Senate should stop trying to promote bills on human rights or democracy in Hong Kong.
"I want to reiterate that Hong Kong is China's Hong Kong. Hong Kong affairs are purely China's internal affairs and cannot be interfered by any external forces," he said at a daily briefing.
Recent weeks have been marked by escalating vandalism of train stations and shops, and assaults by both protesters and pro-Beijing supporters.
Police have arrested more than 3,500 people since the movement began in June over a now-withdrawn extradition bill.
Activists saw the bill as another sign of an erosion in Hong Kong's autonomy and civic freedoms, which China promised would be maintained for 50 years under a "one nation, two systems" principle when the former British colony returned to Chinese control in 1997.