Hong Kong police shot a teenage protester at close range, leaving him bleeding and howling on the ground as anti-government demonstrations in the former British colony erupted into the most widespread violence yet seen against Chinese rule.

Tens of thousands of demonstrators marched yesterday in defiance of a protest ban imposed as Beijing marked the 70th anniversary of Communist rule.

The single pistol shot fired by the officer as protesters advanced towards him hit the 18-year-old on the left side of his chest, a police spokeswoman said. She described the protesters as “rioters” and said the officer had feared for his life.

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Hong Kong’s hospital authority said the teenager was one of two people in a critical condition with a total of 51 injured.

Officers have previously fired warning shots in the air during months of protests in Hong Kong, but this marked the first time a protester was known to have been fired at.

There were other instances yesterday when officers drew their weapons, including two with bloodied faces who pointed pistols, as protesters and riot police fought fierce battles at multiple locations across the city.

A video taken by City University Student Union that spread quickly on social media appeared to show the officer opening fire as the protester came at him with a metal rod and struck the officer’s shooting arm.

It showed a dozen black-clad protesters hurling objects at a group of riot police and closing in on the lone officer who pointed his pistol and opened fire. The protester toppled backwards on to the street, bleeding from below his left shoulder.

As another protester who rushed in to try to drag away the wounded youth was tackled by an officer, a petrol bomb landed in the middle of the group of officers in an explosion of flames.

The shooting marked a dramatic ramping-up in violence that spread chaos to multiple areas of China’s freest and most international city.

Riot police fired multiple volleys of tear gas in at least six locations and used water cannons in the business district of the semi-autonomous Chinese territory as protesters turned streets into battlefields to spoil the October 1 anniversary of Communist rule.

A security clampdown to thwart violence that would embarrass Chinese President Xi Jinping failed to deter the protests, including a massive march in the city centre.

Organisers said at least 100,000 people marched along a broad city thoroughfare in defiance of a police ban, chanting anti-China slogans and some carrying Chinese flags defaced with a black cross.

Many demonstrators tossed wads of fake “hell” banknotes usually used at funerals into the air. “The leaders who won’t listen to our voice, this is for them,” said marcher Ray Luk.

Thousands of people confronted police in multiple locations across the city, the largest number of simultaneous protests since the unrest began in early June over a now-shelved extradition bill that activists say was an example of how Hong Kong’s freedoms and citizens’ rights are being eroded.

The movement has snowballed into an anti-Chinese campaign with demands for direct elections for the city’s leaders and police accountability.

The smell of tear gas and smoke from street fires started by protesters engulfed the Wan Chai, Wong Tai Sin, Sha Tin, Tuen Mun, Tsuen Wan and Tsim Sha Tsui areas. 

Protesters hurled petrol bombs, bricks and other objects at police, who responded with volleys of tear gas. Protesters used umbrellas as shields and threw tear gas canisters back at officers. Police said protesters used corrosive fluid in Tuen Mun, injuring officers and some reporters.

In Wong Tai Sin, a petrol bomb hurled at police exploded near motorcycles parked along a pavement, creating a large blaze that was put out by firefighters. Some protesters placed an emergency water hose down a subway station to try to flood it.

A water cannon truck sprayed blue water, used to identify protesters, to disperse crowds from advancing to government offices in the city. Scores of police officers also stood guard near Beijing’s liaison office as the battles continued.

“Today we are out to tell the Communist Party that Hong Kong people have nothing to celebrate,” said activist Lee Cheuk-yan as he led the central march.

“We are mourning that in 70 years of Communist Party rule, the democratic rights of people in Hong Kong and China are being denied. We will continue to fight.”

Activists carried banners saying “End dictatorial rule, return power to the people”.

The protests contrasted with Beijing’s anniversary festivities marked with a colourful parade and display of new missile technology.

Hong Kong chief executive Carrie Lam, who was in Beijing for the ceremony, smiled as a Hong Kong float passed by.