Hong Kong students armed with bows and arrows and hurling gasoline bombs battled police firing tear gas and blasting water cannons as escalating violence paralyzed the educational system of the beleaguered semi-autonomous Chinese territory.

Late Sunday, police used loudspeakers to order the evacuation of Hong Kong Polytechnic University. Many protesters stayed behind, some setting fires to block the advance of riot police.

"Rioters recklessly vandalized facilities and hurled bricks and petrol bombs at police officers, jeopardizing public safety," police said in a statement. Police released an image of what appears to be an arrow stuck in the leg of an officer.

Police said dozens had been arrested. The protest was the final holdout from a series of demonstrations that shut down several major universities last week.

The Hong Kong Education Bureau announced that all schools would close again Monday "for the sake of safety" across the territory of 7.4 million people. Classes from kindergarten up for almost 1 million students were also canceled Thursday and Friday due to the impact of the protests on traffic and public transportation.

"All parties should immediately put a halt to all violent and destructive activities so that students can return to their normal school life," the department said. "If the situation allows, schools may resume classes on Tuesday."

Five university presidents issued a joint statement urging both sides of the conflict to exercise restraint. Auxiliary Bishop of Hong Kong Joseph Ha Chi-shing, who traveled to the school, pleaded and prayed for a de-escalation before the violence leads to deaths.

Some universities have cut short their fall semesters. In the U.S., Georgetown University and Syracuse University announced last week that they canceled study abroad programs in Hong Kong for the remainder of the semester due to protests in the region.

American universities terminating Hong Kong study abroad programs early

A government extradition proposal earlier this year that would have allowed suspects in Hong Kong to be sent to mainland China sparked months of massive, sometimes violent protests. The Hong Kong government withdrew the proposal, but protesters have seized the momentum to press demands for more freedoms and investigations into police behavior during the protests.

More than 3,000 protesters have been arrested since the protests began five months ago.

Hong Kong protesters blame police: Student dies in fall

Hong Kong was controlled by Great Britain for more than 150 years until 1997 when it ceded control to China. The wealthy, free-market city became a special administrative region that was promised a “high degree of autonomy" for 50 years.

Pro-democracy residents of Hong Kong have long accused China of slowly encroaching on that autonomy.

Congressional leaders have blamed the Chinese government for the unrest and warned Beijing against using force to quell protests. President Donald Trump, locked in a trade war with China, has generally avoided criticizing Beijing for its Hong Kong policy. Trump has described the situation as "tough" and "tricky."