By Jessie Pang and Donny Kwok

HONG KONG (Reuters) – Hong Kong police shot a teenager on Tuesday, the first time a protester has been hit by live ammunition during four months of demonstrations, as the Chinese-ruled city was rocked by widespread unrest on the 70th anniversary of the founding of the People’s Republic.

In cat-and-mouse clashes that spread from the upmarket district of Causeway Bay to the Admiralty area of government offices on Hong Kong island, police were pelted with petrol bombs and responded by firing tear gas and water cannon.

Police said an officer shot an 18-year-old man in the shoulder in the Tsuen Wan area of the New Territories with a live round. Protesters have previously been hit before with bean bags rounds and rubber bullets and officers have fired live rounds in the air.

Verified video footage of the incident widely shared on social media shows a chaotic melee with riot police battling protesters wielding metal bars, before an officer fires a shot at close range.

As the wounded man steps back and falls, someone tries to help, but another policeman tackles him to the ground.

“A large group of rioters was attacking police officers in Tsuen Wan,” police said in a statement. “Police officers warned them, but they were still attacking police. A police officer’s life was seriously endangered. In order to save his and other officers’ lives, they fired at the attacker.”

There were no immediate details on the wounded man’s condition.

Former colonial ruler Britain said the use of live ammunition was disproportionate.

Nearly four months of street clashes and demonstrations have plunged the former British colony into its biggest political crisis in decades and pose the most serious popular challenge to President Xi Jinping since he came to power.

Protesters had vowed to seize the opportunity on China’s National Day to propel their calls for greater democracy onto the international stage, hijacking an occasion Beijing sees as an opportunity to showcase China’s economic and military progress.

“I’m not young, but if we don’t march now, we’ll never have the chance to speak again, it’s as simple as that,” said one marcher near Causeway Bay, a 42-year-old woman with her own logistics company who identified herself as Li.

POLICE BAN DEFIED

Thousands of black-clad protesters, some wearing Guy Fawkes masks, marched on Admiralty, defying a police ban. Violence escalated across the harbor to Kowloon and beyond to the New Territories. Police vans chasing down pro-democracy protesters in the key drag of Hennessy Road.

Police said 31 people had been wounded across the territory, two critically, without giving details.

Protester Jerry, 26, dressed in black and sitting amid the wreckage in Causeway Bay, denounced the police.

“The Hong Kong police, they’ve just lost their minds,” he told Reuters. “They just follow orders. They say it’s to protect lives, but they see the people as objects.”

British Foreign Secretary Dominic Raab criticized the use of live ammunition.

“Whilst there is no excuse for violence, the use of live ammunition is disproportionate, and only risks inflaming the situation,” Raab said in a statement.

In the Admiralty area, police fired water cannon and volley after volley of tear gas to disperse protesters throwing Molotov cocktails outside central government offices and ordered the evacuation of the Legislative Council building next door.

Petrol bombs were also thrown at MTR metro stations, including at Causeway Bay and Admiralty and Sham Shui Po in the New Territories. Many stations were closed to stop protesters moving around. Shutting stations has made them a common target for attack during the weeks of unrest.

Chinese banks and Chinese-backed businesses were targeted with petrol bombs and anti-China graffiti. Local broadcaster RTHK said it was pulling all its reporters away from the violence after one was hit on the head.

BIRTHDAY PARADE

Hong Kong has been tense for weeks, with protests often turning violent, as authorities tried to avoid activists spoiling Beijing’s birthday parade.

Hundreds of officials and members of Hong Kong’s pro-establishment elite began the day with a flag-raising ceremony and National Day reception at the Convention and Exhibition Centre, held early and moved behind closed doors. Roads to the center were closed and tightly policed.

Hong Kong had benefited from China’s support under the “one country, two systems” policy, Acting Chief Executive Matthew Cheng told the assembly, referring to guarantees of political freedoms after the city’s handover from British to Chinese rule in 1997.

But he said escalating violence was disrupting social order and hurting the economy.

The government of embattled leader Carrie Lam has already canceled an annual Oct. 1 fireworks display over the city’s Victoria Harbour, citing public safety.

Lam, who was trapped in a stadium for hours last week after attending the “open dialogue”, left for Beijing on Monday to celebrate China’s birthday on the mainland.

In contrast to events in Hong Kong, Beijing’s carefully choreographed anniversary festivities included troops marching through part of Tiananmen Square with new missiles and floats celebrating the country’s technological prowess.

Lam was shown on television smiling as a float celebrating Hong Kong went past as she sat with Chinese officials.

The Communist Party leadership is determined to project an image of national strength and unity in the face of challenges including Hong Kong’s unrest.

“On our journey forward, we must uphold the principles of peaceful reunification and one country, two systems; maintain lasting prosperity and stability in Hong Kong and Macau … and continue to strive for the motherland’s complete reunification,” Xi said in a nationally televised speech in Beijing.

Hong Kong protesters are angry about what they see as creeping Chinese interference in the Asian financial center.

China dismisses the accusation and has accused foreign governments, including the United States and Britain, of fanning anti-China sentiment.

(Reporting by Jessie Pang and Donny Kwok, Additional reporting by Sharon Tam, Felix Tam, Poppy McPherson, Anne Marie Roantree, Farah Master, James Pomfret, Twinnie Siu, Alun John, David Kirton, Jennifer Hughes and Keith Zhai; Writing by Clara Ferreira Marques, Bill Rigby and Nick Macfie; Editing by Raju Gopalakrishnan and Alex Richardson)