Hong Kong police fired tear gas, rubber bullets and water cannons on Saturday, while protesters launched Molotov cocktails, as anti-government demonstrations that have roiled the territory for months once again turned violent.

Police fired round after round of tear gas as protesters took cover behind umbrellas between the local headquarters of China's People's Liberation Army and government HQ. Protesters also pointed lasers and threw bricks at police.

The water cannon fired blue-dyed water, traditionally used elsewhere in the world to make it easier for police to identify protesters later. ANTHONY WALLACE / AFP - Getty Images

Fears of clashes were running high ahead of the demonstrations, aimed at marking the fifth anniversary of a decision by China to curtail democratic reforms in the former British colony.

Police rejected a permit application for protesters to hold the rally and also detained and released two prominent protest organizers ahead of Saturday's march — a move which international human rights group Amnesty International called "an assault on their rights to freedom of expression and peaceful assembly."

Official protest organizers told NBC News on Friday that they were pulling out of demonstrations but both protest organizers and police said an assembly of activists was still expected and could turn violent.

Joshua Wong, one of the protesters who was released on bail Friday, spoke out against police and the government in a series of tweets defending his actions. "Our freedom of assembly and other fundamental rights are eroded," he said. "Hongkonger, together we stand! We shall never surrender!"

Even Beijing and HKGov arrested and prosecuted me & @chowtingagnes, we will not surrender even after we were charged with organising, leading and participating illegal protest.



Hong Kong should not be a full-fledged authoritarian police state! pic.twitter.com/XReCv0Vk5e — Joshua Wong 黃之鋒 (@joshuawongcf) August 30, 2019

On Saturday, demonstrators — many wearing black and face masks — marched in disparate groups throughout Hong Kong in the rain communicating with different hand signals and chanting "stand with Hong Kong" and "fight for freedom."

Although the event began peacefully with families, including young children participating, clashes eventually broke out with police.

Water cannons sprayed at the protesters to disperse crowds contained blue and red dye — a tactic local media said would help police identify people who participated in the banned rally.

Police fought running battles with protesters, beating them with truncheons.

The city's subway operator suspended some services and shut station exits because of likely "public activities."

The House Committee on Foreign Affairs released a bipartisan statement Saturday condemning China for having "undermined the autonomy of Hong Kong, exacerbated existing grievances" while calling the actions of protesters "admirable."

The statement, issued by Rep. Eliot Engel, D-NY, and Rep. Michael McCaul, R-TX, also called on authorities to release anyone detained on politically motivated charges and stop the use of excessive force against protesters.

"We urge authorities to exercise restraint and both sides to refrain from violence and seek a peaceful accommodation that addresses the legitimate concerns of the people of Hong Kong," Engel and McCaul said.

Protesters march in the Central district of Hong Kong on Saturday. ANTHONY WALLACE / AFP - Getty Images

The demonstrations that have plunged the former British colony into a political crisis began in June after Hong Kong's chief executive Carrie Lam proposed a controversial extradition bill.

The bill raised fears that the rights of Hong Kong's 7 million residents were being eroded under Beijing's rule, as it would allow suspects to be sent to China.

Hong Kong became a special administrative region of China in 1997. Unlike those living in the mainland, residents of the territory can freely surf the internet and participate in public protests.

Demonstrations have since morphed from calling for the withdrawal of the extradition bill to include demands that Lam resign and allegations of police brutality be investigated.

Many have feared Beijing could intervene in the unrest as the 70th anniversary of the founding of the People's Republic of China looms on Oct. 1.

Its People's Liberation Army troops in the territory were rotated on Thursday.