Hong Kong police stormed a university barricaded by protesters early Monday morning, leaving the entrance in flames. Protesters took over Hong Kong Polytechnic University in recent days, and police began moving in early Monday morning after one police media liaison officer was struck in the calf with an arrow on Sunday. Police warned protesters on Monday that they would fire live rounds if the “rioters” did not stop using lethal weapons, in the latest development in six months of protests for democracy throughout the city. “We will use the minimal force,” police said in a Facebook video. “We are asking the rioters to stop assaulting the police using cars, gas bombs, and bows and arrows. Otherwise we will use force including live rounds.” The confrontation began early Sunday when police pummeled protesters with tear gas and water cannons. Police announced at 9 p.m. that the “next round of operation” was beginning, and said they would arrest protesters on charges of rioting, which has a maximum sentence of 10 years in prison in Hong Kong.