Tear gas was fired later on Sunday night during confrontations involving police, protesters and residents. The Post understands that 35 people were arrested on Sunday, when protests took hold in shopping centres in several parts of the city.

One of the victims of the knife attack, a man, was seen lying in a pool of blood in the Hong Kong Island neighbourhood of Tai Koo. The suspect, a Mandarin speaker, was stopped at the scene by a crowd, who then beat him up.

Another victim, who sustained relatively minor injuries, said she, her sister and her brother-in-law had just left the Cityplaza mall after dinner when an argument broke out with the suspect, who retrieved a knife from his bag. He had argued with her sister and her sister’s husband, who was attacked.

Among the injured was district councillor Andrew Chiu Ka-yin.

Democratic Party lawmaker James To Kun-sun said he met some witnesses of the attack in hospital as he, along with several colleagues, visited Chiu. 

“They heard the attacker shouting ‘liberate Taiwan’ before he waved his knife. It is believed to be a premeditated attack as he carried the knife with him,” To said.

He said Chiu was there trying to mediate.

Four men and two women were injured in the incident. Five were sent to Pamela Youde Nethersole Eastern Hospital in Chai Wan, while one did not need to go for treatment.

As of 10am on Monday, two of the men remained in critical condition in hospital, including the suspect, and another two people were in serious condition. One man was stable.

A video posted online showed the suspect wrestling with Chiu while others punched the man in a bid to force him to release the councillor. The attacker then bit off the edge of Chiu’s ear, spitting it on the ground.

The incident came as riot police were deployed in several shopping malls – including Cityplaza – across Hong Kong after hundreds of people heeded an online call to take to the streets on Sunday afternoon in an unlawful citywide protest.

The Hospital Authority said on Monday morning that 17 people, aged between 19 and 55, were injured during protests across the city on Sunday.

Amid the unrest, police also entered malls in the New Territories towns of Sha Tin and Tai Po.

The actions came after protesters damaged turnstiles at Sha Tin MTR station, threw objects at police and vandalised a restaurant in Tai Po, and formed human chains in Tai Koo.

A poster for the event urged people to gather in those seven districts at 1pm.

Late into the night, protesters built roadblocks on Tai Po Tai Wo Road, in Tai Po. After midnight, in the residential area around Sheung Tak Estate and Kwong Ming Court in Tseung Kwan O, police fired multiple rounds of tear gas as protesters threw bricks and built roadblocks.

About 200 people were still gathered in Tseung Kwan O at 2am. During the confrontation, a student from Hong Kong University of Science and Technology fell from the third floor of Kwong Ming Court’s car park to the second floor in what local media reported was an attempt to flee tear gas. He was sent to hospital but his condition remained unknown.

In the afternoon in Sha Tin New Town Plaza, a group of about 50 black-clad protesters took over the atrium of the shopping centre, chanting slogans.

At one point, some were seen breaking MTR turnstiles at the train station’s entrance in the mall. Riot police moved in quickly, only to be confronted by protesters, who shouted abuse at officers. Police reportedly took away at least five people.

Some shops pulled down their shutters. Police guarding the mall’s upper levels used pepper spray to disperse the crowd down in the atrium while some on the ground pointed their firearms at people on floors above.

Some protesters hurled verbal abuse, daring police to fire tear gas at them.

At least three onlookers received medical treatment in the mall after being pepper-sprayed. A middle-aged man was given an ice pack after pepper spray hit his forehead. Paramedics gave a young man an oxygen mask after he said he had asthma.

A 54-year-old woman, surnamed Wong, who moved to Hong Kong from mainland China 10 years ago, said: “The actions of police are despicable. They can’t just come into shopping malls and do this to young people.

“I realised there was a lot that I didn’t know before I came to Hong Kong. I really like it here, but the government is now trying to control the way people act and think. It is oppressing its citizens.”

Earlier, a national flag was removed from a pole at Sha Tin Town Hall. The flag was later found on a road near a highway.

In Tai Po Mega Mall, a group of masked black-clad demonstrators targeted a branch of restaurant chain Yoshinoya in what they called a flash mob protest. There were no diners or employees around as the vandals broke in.

Later, in chaotic scenes in the mall, there were scuffles between police in riot gear and people who threw various objects at officers. Police took away at least three people.

Police also raised a black flag in Tai Po, warning of the use of tear gas, as people targeted them with laser pointers. Officers then displayed an orange flag, telling the crowd to disperse or they would fire. Police also rushed into the mall after objects were thrown from on high.

Also in the New Territories, at Tuen Mun’s Trend Plaza, locals tried to lock the doors of the shopping centre with plastic cords to stop police from entering.

Previously, a group of about 50 riot police had raised the blue flag warning of an illegal assembly on the podium outside the mall, searching bags and asking young people and other residents for their identity cards. The checks were carried out after eggs and a ladder were thrown from the podium to the ground floor. No one was hurt.

There were also scuffles when a group of black-clad protesters surrounded a man in a blue shirt, claiming he had taken pictures of them. The man later left unharmed.

Police condemned the act of blocking the mall exit, calling it dangerous and irresponsible.

Trend Plaza, which is owned by developer Henderson Land, announced in a shopping mall broadcast that it was closing. At about 5.30pm, security staff started closing the mall’s doors.

On Hong Kong Island, more than 200 protesters had gathered in Cityplaza and were chanting slogans. Shops were open for business as usual when riot police rushed in shortly after 6pm. They pinned down at least one protester.

A photographer from Stand News was arrested in the mall while working, the online media outlet confirmed.

“[He] was wearing a reporter’s badge, and the cause and process of the arrest have not been clear,” it said, adding the employee had been covering protests professionally since June. It demanded that police state clearly why he was detained.

Angry residents surrounded security staff at Cityplaza demanding answers over the police presence in the mall. Security staff told media they did not call police.

Cityplaza Management Office said in a statement it was not informed by police before officers entered the premises at 6.15pm.

“However, in an emergency situation or in response to a 999 call, police are not obliged to inform us in advance before they enter our premises as the Police Force Ordinance gives them the power of entry,” the statement read.

The office added it regretted the confrontation and strongly condemned the violence.

Police said they entered the mall because protesters were vandalising a restaurant.

A government spokesman condemned the violence in Sha Tin, Tuen Mun, Tai Po and Tai Koo.

“The government deeply regrets and severely condemns the violent attack in Tai Koo. We appeal to people with different opinions to lay down their differences,” the spokesman said.

“To ensure public safety and uphold the rule of law, police must take decisive action, arrest suspected offenders, and strictly enforce the law to restore social order as soon as possible.”

Additional reporting by Karen Yeung, Karen Zhang, Tony Cheung and Alvin Lum