The streets of downtown Hong Kong turned into the site of clashes between protesters and police on Sunday as the political turmoil continues in the global financial center for a 15th straight weekend.

Tens of thousands of pro-democracy supporters marched through downtown in defiance of a police ban before violence broke out later in the day as police fired chemical-laced blue water meant to mark protesters as well as tear gas at demonstrators who lobbed Molotov cocktails outside the Hong Kong government office complex.

Hospital authorities said eight people were injured throughout the day, including three in serious condition.

Authorities had turned down a request by the Civil Human Rights Front to hold the march, but the demonstrators were undeterred. Instead, a mixed crowd made up of hardcore protesters in black wearing masks alongside families with children marched for more than 1.2 miles, some waving U.S. and British flags.

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“We hope our children have a future, because now in Hong Kong, we cannot see any hope,” a woman named Charis, who brought her 7-month old daughter to the demonstration, told the Wall Street Journal. “We need to stand here, we need to walk here."

An anti-government protester throws a Molotov cocktail during a demonstration near Central Government Complex in Hong Kong, Sunday, Sept. 15, 2019. (AP Photo/Vincent Yu)

The march featured protesters who burned Chinese flags and tore down banners congratulating China's ruling Communist Party, which will celebrate its 70th year in power on Oct. 1. In familiar scenes, some protesters smashed glass windows and surveillance cameras at a subway station exit.

Some protesters also carried large American flags and a large banner that read, "President Trump Please Liberate Hong Kong."

Protesters carry U.S. flags during a rally in Hong Kong, Sunday, Sept. 15, 2019. (AP Photo/Vincent Yu)

Many in the crowd also sang “Glory to Hong Kong,” a new anthem of the protest movement, according to videos from those at the scene.

Earlier Sunday, hundreds of protesters waved British flags, sang "God Save the Queen" and chanted "UK save Hong Kong" outside the British Consulate as they stepped up calls for international support for their campaign.

Protesters carry a British flag gather at a shopping district during a rally in Hong Kong, Sunday, Sept. 15, 2019. (AP Photo/Kin Cheung)

With banners declaring "one country, two systems is dead," they repeated calls for Hong Kong's former colonial ruler to ensure the city's autonomy is upheld under agreements made when it ceded power to China in 1997. Demonstrators held similar rallies Sept. 1 at the British facility and last weekend at the U.S. Consulate.

The marches disrupted traffic, and many shops, including the Sogo department store in Causeway Bay, one of Hong Kong's largest department stores, closed their doors.

Hundreds of protesters later targeted the government office complex, throwing bricks and petrol bombs through police barriers. They were met by police responding with tear gas and water cannon trucks to spray chemical-laced water as well as a blue liquid to help them identify suspects.

A police vehicle sprays blue-colored water towards anti-government protesters during a demonstration near Central Government Complex in Hong Kong, Sunday, Sept. 15, 2019. (AP Photo/Kin Cheung)

Protesters retreated, but regrouped in the nearby Wan Chai neighborhood, setting a fire outside a subway station exit and on the streets. They fled again after riot police advanced.

Several fights were also reported on city streets, according to the South China Morning Post.

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Various videos on social media showed people clashing on city streets into the night.

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Police had earlier warned in a statement that the assembly was illegal and urged protesters to "stop their illegal acts."

The protests were triggered in June by an extradition bill that many saw as an example of China's increasing intrusion and at chipping away at Hong Kong residents' freedoms and rights, many of which are not accorded to people in mainland China.

Hong Kong's government promised this month to withdraw the bill, which would have allowed some criminal suspects to be sent to mainland China for trial, but protesters have widened their demands to include direct elections for the city's leaders and police accountability.

More than 1,300 people have been arrested amid increasing clashes between protesters and police, who demonstrators have accused of abuses.

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The unrest has battered Hong Kong's economy, which was already reeling from the U.S.-China trade war. It is also seen as an embarrassment to Beijing, which has accused foreign powers of fomenting the unrest.

Thousands of Hong Kong people chanted slogans and marched Sunday at a downtown shopping district in defiance of a police ban. (AP Photo/Vincent Yu)

Police also banned a planned Civil Human Rights Front march on Aug. 31, but protesters turned up anyway. Clashes erupted that night, with police storming a subway car and hitting passengers with batons and pepper spray.

On Saturday, pro-democracy protesters and supporters of the central government in Beijing clashed at a Hong Kong shopping mall and several public places. Police arrested more than a dozen people and hospital authorities said 25 were injured.

The Associated Press contributed to this report.