Hong Kong’s embattled leader Carrie Lam said on Tuesday she hoped a standoff between police and a hold-out group of anti-government protesters at a university could be resolved and she had told police to handle it in a humane way.

A last group of about 100 defiant protesters remain in the Hong Kong Polytechnic University after more than two days of clashes with police surrounding it in which more than 200 people have been injured.

Lam spoke at a news conference shortly after the city’s new police chief urged the support of all citizens to end five months of unrest, triggered by fears that the Beijing government is stifling the city’s special autonomy and freedoms.

Lam said her government was very much on the “reactive side” but did not rule out further violence even as she urged peace.

“If the protesters are coming out in a peaceful manner … then there is no situation when that sort of violence would happen,” she said.

But if the situation changed, police would have to take “necessary action,” she said, adding she had been shocked that campuses had been turned into “weapons factories.”

Dramatic escape

Lam said 600 protesters had left the campus, including 200 below the age of 18.

The university is the last of five that protesters occupied to use as bases from which to disrupt the city, blocking the city’s central cross-harbour tunnel and main roads, and forcing the closure of businesses including shopping centres, in order, they said, to put the government under economic pressure.

Hundreds of protesters fled from the university or surrendered overnight amid running battles on surrounding streets as police fired tear gas, water cannon and rubber bullets and protesters lobbed petrol bombs and bricks.

WATCH: Police arrest protesters in Hong Kong

Police used tear gas to try to clear protesters from the Polytechnic University. 0:42

At one stage, dozens of mask-wearing protesters staged a dramatic escape from the campus by shimmying down plastic hosing from a bridge and fleeing on waiting motorbikes as police fired projectiles.

Canadians affected

Global Affairs Canada said to CBC News in a statement that it is “aware of Canadians affected and we are in contact with local authorities.”

Asked if those Canadians have been arrested, injured or are still protesting, a spokesperson would not comment, citing “provisions under the Privacy Act.” 

A protester is detained by police as he tries to escapes from Hong Kong Polytechnic University on Monday. (Getty Images)

The University of British Columbia confirmed in a statement Monday that 11 of its exchange students have left Hong Kong and the 21 remaining in the city are safe and accounted for. An official says they are assisting the students with travel planning. 

Montreal’s McGill University, which has a partnership with Hong Kong Polytechnic, says all 17 of its students are accounted for.

Fear and desperation

The University of Toronto and Queen’s University in Kingston, Ont., are also urging all of their exchange students to head home.

Police allowed two prominent figures onto the campus late on Monday to mediate but many protesters refused to leave even though food was running out.

Anti-government protesters walk past a fire during clashes with police at Hong Kong Polytechnic University (PolyU) on Monday. (Laurel Chor/Getty Images)

“There have been so many people who have sacrificed for this,” said a 21-year-old university student, who identified himself as T, after escaping from the university on Tuesday.

Tang Siu Wa, a protester inside the university, told CBC News Network there is fear and desperation inside the campus.

‘I can’t abandon them’

Trust between police and protesters is totally lost, she said.

There is a path to leave the university, she said — but those who take it risk arrest.

“They want to arrest a large number of protesters,” she said. “They want … to quiet the movement.”

WATCH: Protester describes the atmosphere inside the campus

CBC News Network’s Michael Serapio spoke to pro-democracy protester Tang Siu Wa inside Polytechnic University in Hong Kong. 5:41

She said police weren’t trying to come into the campus, but were trying to isolate protesters and limit their access to supplies. When asked whether she would stay to the end, she said she had chances to leave the campus but decided to stay.

“I don’t want to leave the youngsters,” she said. “They are the age of my son or daughter … and they are fighting for the future of Hong Kong.

“I can’t abandon them.” 

Police says they’ve shown restraint

Many protesters say they fear even more bloodshed with no resolution in sight to a standoff that has seen some of the most intense violence in what has become the worst crisis since Hong Kong’s return from British to Chinese rule in 1997.

Protesters were initially angered by a now-shelved bill that could have sent people to mainland China for trial but has since broadened into calls for full democracy and an end to what many see meddling by Beijing in China’s freest city.

China says it is committed to the “one country, two systems” formula introduced in 1997 granting Hong Kong autonomy and has accused foreign countries, including Britain and the United States, of inciting trouble.

The city’s police deny accusations of brutality and say they have shown restraint.

China questions Hong Kong court’s power

But the city’s autonomy has been thrown into question after China’s top legislature questioned the power of the city’s High Court to overturn a government emergency ban on face masks worn by protesters.

A spokesperson for the legislative affairs commission of the Standing Committee of China’s National People’s Congress, said Hong Kong courts had no power to rule on the constitutionality of the city’s legislation, the state Xinhua news agency reported.

Newly appointed Police Commissioner Chris Tang, meanwhile, warned of an “institutional mismatch” that his 30,000-strong force was having to contend with.

“There is a massive scale of breaking of law in Hong Kong and there is a certain sector of the community that also condones that illegal activity,” Tang said in a brief public appearance.

WATCH: Students leave the university, surrender to police

A group of student protesters appeared to leave Hong Kong Polytechnic University voluntarily in the early hours of Tuesday, telling a Reuters journalist they were surrendering to police. 1:05

He also said “fake news” was undermining the reputation of the force that had long been known as one of Asia’s finest.

The number of people demonstrating has fallen in recent weeks but clashes have worsened since last week, when police shot a protester, a man was set on fire and the city’s financial district was filled with tear gas in the middle of the workday.

Hundreds of injuries

Police spokespeople said they fired three live rounds early on Monday but no one was hurt.

Protesters have torched buildings, infrastructure and shops.

The city’s Cross Harbour Tunnel linking Hong Kong island to the Kowloon peninsula remained shut on Tuesday due to extensive damage, authorities said.

Some train services and many roads across Kowloon remained closed. All schools were shut again on Tuesday, extending a string of closures since last week due to safety concerns.

The city’s hospital authority reported 221 injuries over the past day with 12 people in serious condition.

The unrest poses the gravest popular challenge to Chinese President Xi Jinping since he came to power in 2012.

In Washington, U.S. Secretary of State Mike Pompeo told reporters the United States was “gravely concerned” and said the Hong Kong government bore primary responsibility for ensuring a return to calm.