HONG KONG (Reuters) - Hong Kong pro-democracy protesters paralyzed parts of the city for a fourth successive day on Thursday, forcing schools to close and blocking highways, as students built campus barricades and the government dismissed rumors of a curfew.

Protesters have torched vehicles and buildings, hurled petrol bombs at police stations and trains, dropped debris from bridges on to traffic below and vandalized shopping malls and campuses, raising questions about how and when more than five months of unrest can be brought to an end.

A 70-year-old street cleaner who was believed to have been hit in the head by a brick on Wednesday died on Thursday, the hospital said. Police said he was believed to have been hit by “hard objects hurled by masked rioters” during his lunch break.

Chinese President Xi Jinping, speaking in Brazil, said stopping violence was the most urgent task right now for Hong Kong, China’s state CCTV television reported.

He said China continued to firmly support Hong Kong leader Carrie Lam. China has a garrison of up to 12,000 troops in Hong Kong who have kept to barracks, but it has vowed to crush any attempts at independence, a demand from a very small minority of protesters.

The unrest was triggered by what many see as the stifling by China of freedoms guaranteed under the “one country, two systems” formula put in place when Hong Kong returned to Chinese rule in 1997.

China denies interfering in Hong Kong and has blamed Western countries, including Britain and the United States, for stirring up trouble.

Anger grew over perceived police brutality as the protests intensified. Police deny being heavy handed and say they have shown restraint in the face of potentially deadly attacks.

“HIGH-SPIRITED RIOTERS”

Thousands of students hunkered down at several universities on Thursday, surrounded by piles of food, bricks, petrol bombs, catapults and other homemade weapons.

Police said the Chinese University, in the New Territories, had become a “weapons factory and an arsenal” with bows and arrows and catapults.

“Their acts are another step closer to terrorism,” Chief Superintendent (Public Relations) Tse Chun-chung told a briefing, referring to protests on campuses across the Chinese-ruled city.

He also said police would temporarily avoid directly clashing with “high-spirited rioters” to give themselves a breather and avoid injuries.

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Police said arrows were fired at officers from Hong Kong Polytechnic University in the morning. Several Hong Kong universities announced there would be no classes on campuses for the rest of the year.

During the apparent lull in police action, thousands were milling about on Nathan Road, the main artery leading south through the center of Kowloon to the harbor, building a wall from bricks. Police had fired tear gas earlier on the street earlier in the evening.

Baptist University, next to a People’s Liberation Army base in Kowloon Tong, issued an “urgent appeal”, telling students to stay away from campus.

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“Your safety is so dear to our hearts and to your parents’ and friends’ hearts,” it said. “Please stay away from harm’s way.”

China’s Global Times tabloid, owned by the official newspaper of the ruling Communist Party, the People’s Daily, said on Twitter that the Hong Kong government was expected to announce a weekend curfew after some of the worst violence in decades in the former British colony.

It deleted the post after a short time. The Hong Kong government said the rumors were “totally unfounded”.

PETROL BOMBS AND BRICKS

Hundreds of protesters occupied roads in the city’s business district, home to some of the world’s most expensive real estate, in the middle of the day.

Across the harbor, black-clad protesters and students maintained their blockade of major roads, including the entrance to the Cross-Harbour Tunnel that links Hong Kong island to the Kowloon area, and a highway between Kowloon and the rural New Territories.

Police fired tear gas near the tunnel early on Thursday to try to clear the protesters. Protesters threw petrol bombs at the Kowloon-side tunnel turnstiles late in the evening and the tunnel remained closed.

At the Polytechnic University, near the same tunnel entrance, hundreds of students wearing gas masks readied for confrontation. They were practising throwing petrol bombs and archery in a half-empty swimming pool.

Boxes of petrol bombs were placed at vantage points overlooking roads.

Violence has escalated in recent days, with police shooting and wounding one protester at close range and one man described as a “rioter” dousing a man with petrol before setting him on fire. Several others have been wounded.

The man who was shot was in stable condition. The man who was lit on fire suffered burns to his torso and head, and was in critical condition.