HONG KONG (Reuters) -- Hong Kong police fired multiple tear gas rounds on Saturday night in confrontations with black-clad activists in the city's Kowloon area, as the Chinese-controlled territory was again rocked by anti-government protests.
Police had kept out of sight during the afternoon as tens of thousands of protesters marched through Mong Kok, usually a busy shopping district. But they charged onto the streets after 9 p.m. (1300 GMT), with hundreds of officers in riot gear pushing back crowds who jeered them.
At around midnight in Wong Tai Sin, a residential area, protesters hurled umbrellas and other objects at police, who responded with pepper spray and then tear gas.
Throughout the evening in Kowloon, police confronted protesters who retreated and regrouped. Some were detained.
Protests against a proposed bill allowing people to be extradited to stand trial in mainland China have grown increasingly violent since June, with police accused of excessive force and failing to protect protesters from suspected gang attacks.
On Saturday, protesters set fires in the streets, outside a police station and in rubbish bins, and blocked the entrance to the Cross-Harbour Tunnel, cutting a major artery linking Hong Kong island and the Kowloon peninsula.
"I've never seen anything like this. The protesters are right, but they shouldn't be violent," said Ray, 57, a retired hotel worker who came from his flat on a side street near where police and protesters were in a stand-off.
"The government should listen to the people and what they need," he said.
In a statement issued after midnight, the Hong Kong government said it "strongly condemns the radical protesters."
After the afternoon march, protesters had dispersed to different parts of Kowloon, setting up barriers across busy streets to block traffic. Many carried hiking sticks and some held homemade shields.
Protesters, many masked and wearing helmets and goggles, have adopted increasingly sophisticated tactics.
"We don't stay in the same place. We are using hit-and-run tactics," said a construction worker in Mong Kok who called himself "Water".
"If the police are too strong, we will leave. They are a rock, so we must be like water," he added, echoing a refrain of Hong Kong martial arts legend Bruce Lee that has been taken up by activists.
Organizers said 120,000 people joined the rally. Police said 42,000 people had joined the march at its peak.
In the Nathan Road area, normally packed on a Saturday, shops were shuttered, including 7-11 convenience stores, jewellery chain Chow Tai Fook and watch brands Rolex and Tudor.
The main entrance to the landmark Peninsula Hotel was closed.
Protesters -- many wearing yellow or white hard hats -- chanted "age of revolution!" and "Hong Kongers, add oil!" -- a popular exhortation in Cantonese.
Earlier, marchers carried posters showing protesters tending to a young child, with the words "protect the future". The crowd was mostly young, but also included families and older people. Some young couples held hands.
At a separate afternoon rally in Hong Kong island's Victoria Park, thousands of people, mostly wearing white, with many waving Hong Kong and Chinese flags, shouted slogans in support of the police.
Pro-Beijing lawmaker Junius Ho was greeted with strong applause.
"We are the real Hong Kong people who are not the same as those black-shirted thugs. We don't need a so-called 'HK revolution', we only need to do our best, which is enough," he told the crowd.
Sylvia Lam, 61, who described herself as a housewife, said she had turned up at the pro-police rally to oppose violence.
"I feel extremely uncomfortable when every time I watch TV, the scenes are so radical," she said. "Young people should stop and think, don't become someone's political tools, be rational please."
The organiser estimated the size of the Victoria Park crowd as 90,000, while the police said it was 26,000 at its peak.
The protests against the extradition bill have become the most serious political crisis in Hong Kong since it returned to Chinese rule 22 years ago after being governed by Britain.
Hong Kong has been allowed to retain extensive freedoms, such as an independent judiciary, but many residents see as the latest step in a relentless march towards mainland control.
The protests also mark the greatest popular challenge to Chinese leader Xi Jinping since he took office in 2012.
He is already grappling with an escalating trade war with the United States and a slowing economy. This is an especially sensitive year for China's Communist Party leadership, which will mark the 70th anniversary of the founding of the People's Republic on Oct. 1.
Further anti-government protests were scheduled in Hong Kong for Sunday, with activists calling for a mass strike on Monday.
Months of demonstrations are taking a growing toll on the city's economy, as local shoppers and tourists avoid parts of one of the world's most famous shopping destinations.
On Friday evening, thousands of civil servants defied a warning from authorities to remain politically neutral and joined the anti-government protests for the first time.
In Washington on Friday, a bipartisan group of U.S. lawmakers called on the Trump administration to halt future sales of munitions and crowd-control equipment to Hong Kong's police force, which has been accused of using excessive force against protesters.
