Hong Kong's rule of law has been pushed to the "brink of total collapse" after more than five months of protests, police have warned. The warning came as protesters clashed with police across the city on Tuesday. At the Chinese University of Hong Kong, police fired tear gas and rubber bullets at protesters who built barricades on the campus. Earlier in the day, around 1,000 protesters rallied in central Hong Kong during the lunch hour blocking roads Protesters, wearing office clothes, were seen chanting: "Fight for freedom, stand with Hong Kong!" The demonstrations come just a day after the territory saw a marked escalation in violence, with police shooting one activist in the torso. A pro-Beijing supporter was set on fire by anti-government protesters. The protests started in June against a now-withdrawn plan to allow extradition to mainland China, but have since morphed into wider demonstrations, with activists demanding greater democracy and police accountability in Hong Kong. On Tuesday afternoon, police spokesman Kong Wing-cheung hit out at the protesters, saying they had "countless examples of rioters using random and indiscriminate violence against innocent" people. "Hong Kong's rule of law has been pushed to the brink of total collapse as masked rioters recklessly escalate their violence under the hope that they can get away with it," he told reporters, adding that Monday's attack on the pro-Beijing supporter was being investigated as attempted murder. Speaking at the same conference, Supt Li Kwai-wah defended the officer's decision to shoot the protester on Monday. "We found out that our colleague did not only face threat from one person, instead it was a group of people with an organised plan attempting to steal the gun," he said. "In a situation like this, we believe our police are reacting according to the guideline, to protect themselves as well as the people around them." Both the protester and the pro-Beijing supporter remain in hospital, with the latter in a critical condition.