The latest in Hong Kong:

Protesters build barricades, some make weapons as they gather at universities.

Police say protesters are moving a 'step closer to terrorism.'

Hong Kong government says curfew rumours 'totally unfounded.'

Hong Kong pro-democracy protesters on Thursday paralyzed parts of the Chinese-ruled city for a fourth day, forcing schools to close and blocking highways, as students built campus barricades and the government dismissed rumours of a curfew.

Thousands of students hunkered down at several universities, surrounded by piles of food, bricks, petrol bombs, arrows with heads wrapped in cladding, 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 all campuses.

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

WATCH: Hong Kong police call out protesters

Hong Kong police say protesters' increase in violent tactics 'another step closer to terrorism' and welcome new measures to combat it 0:59

China's Global Times tabloid, owned by the state-run People's Daily, the mouthpiece of the Communist Party, said on Twitter 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 rumours were "totally unfounded."

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.

Police said arrows were fired at officers from Hong Kong Polytechnic University in the morning.

An anti-government protester holds a bow during a standoff with riot police at Chinese University of Hong Kong on Thursday. (Tyrone Siu/Reuters)

Several universities announced there would be no classes on campuses for the rest of the year.

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

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

Blockades and tear gas

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 harbour, black-clad protesters and students maintained their blockades 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. Roads were strewn with bricks in Stonehenge-like formations and other debris, causing widespread traffic jams.

WATCH: Protesters build blockade in Hong Kong

Tensions between protesters and police on the rise 0:35

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.

Police kick away bricks placed by demonstrators to barricade a road during a protest in the financial district on Thursday. (Vincent Yu/The Associated Press)

Boxes of petrol bombs were placed at vantage points overlooking roads, including the tunnel, which has been blocked since Wednesday evening.

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.

Anti-government demonstrators gather to protest as officer workers look from an elevated walkway in Hong Kong on Thursday. (Athit Perawongmetha/Reuters)

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.

There was also a tense standoff between chanting protesters and police in the New Territories town of Sheung Shui.

The demonstrations were spurred by what many residents see as the stifling by Beijing of freedoms guaranteed under the one-country, two-systems formula put in place when Hong Kong returned to Chinese rule in 1997.

Anger has grown 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.

Police said they would appoint 100 Correctional Services Department staff, who look after prisons, to reinforce the streets.

"I cannot see how adding 100 special police will help much," democratic lawmaker Tanya Chan told Reuters. "I don't know why the government doesn't adopt measures that can soften the tension rather than intensify conflict."

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