A man was set on fire outside a subway station in Hong Kong and in a separate incident, police shot and critically wounded a protester, marking a dramatic escalation in the unrest in the former British territory.

These were among several violent incidents that rocked the city Monday in what is now the 24th week of demonstrations.

Hong Kong's leader, Carrie Lam, warned that the semi-autonomous Chinese region was nearing the point of no return.

"This large scale of violence has to be condemned by the entire society," she said. "I am calling on citizens to to understand this nature of this incident, they’re violent, catastrophic."

"The violence made by rioters is beyond their demands. They are the enemies against citizens," she said.

Police confirmed that the man who was set alight outside the subway station in Ma On Shan — an incident captured in multiple graphic social media posts — was being treated in a local hospital. Police said this attack was carried out by protesters who had earlier "trashed" the station.

Meanwhile, the protester who was shot underwent surgery at Pamela Youde Nethersole Eastern Hospital in the Chai Wan district, the hospital told NBC News. Police said in a press conference that the unnamed man had undergone surgery and his injuries were not life-threatening.

Riot police detain protesters in Hong Kong on Sunday. Ahmad Masood / Reuters

The shooting at close range marked the third time since demonstrations began that a protester has been injured after police fired gunshots. On Oct. 1, an 18-year-old student was shot in the chest by a policeman while he was trying to attack an officer, video footage appeared to show. Three days later, a 14-year-old boy was shot in the leg by an out-of-uniform officer who was surrounded by protesters.

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Police fired volleys of tear gas at lunch time in the heart of the financial center in some of the most dramatic scenes to grip the city during months of unrest. Some 120 roads were blocked or barricaded, they said, and Molotov cocktails had been thrown onto trains by demonstrators. The protests continued into the night, with police using water cannons in Mong Kok, an area popular with tourists and locals.

The chief superintendent of the Police Public Relations Branch, Tse Chun-Chung, told a press conference that the shooting took place at 7 a.m. (6 p.m. Sunday ET) in the Sai Wan Ho district, where traffic officers were attempting to clear roads after protesters had laid obstacles. After an arrest was made, protesters surrounded an officer, Tse said.

Tse also confirmed that an officer drove a motorcycle through a crowd of protesters at 8 a.m. in the Kwai Fong area. Multiple social media posts show an officer driving repeatedly into a small crowd of black-clad people and Tse said the officer in question had been suspended from all front-duties and place on immediate leave.

Tse said that the incident came after a protester "sprayed unknown liquid at a police officer’s face, causing temporary loss of vision" and after an officer who came to assist was attacked with a hammer.

Some 260 people had been arrested Monday alone, officials said.

The Hong Kong Hospital Authority confirmed that on Monday 64 people — ages 11 to 61 — were being treated. These included five who were in a serious condition and the two who were in critical, it said.

Anti-government demonstrations have riven Hong Kong for almost six months, having started in June as a series of protests triggered by an extradition bill that was later withdrawn.

The protests have since widened to include calls for greater democratic freedoms amid fears of China's increased control over the territory.

A college student became the first person to die in the protests Friday, four days after he fell in a multistory parking lot as police used tear gas on demonstrators in the area.