Protesters vandalized businesses viewed as supporting Beijing, threw molotov cocktails at police stations, set barricades on fire and smashed up subway stations in chaotic scenes that have become familiar to the city after five months of sustained protest.

A journalist photographs police spraying blue dye from a water cannon in Hong Kong on Sunday. (Kim Kyung-Hoon/Reuters)

The huge turnout, estimated by organizers at around 350,000 and including families, children and the elderly, showed that the movement maintains widespread support in the face of the increasingly violent tactics of protesters and the escalating use of force by police.

Marchers made a sea of colored umbrellas through the narrow streets of the city’s Kowloon area, which are lined with malls and international hotels. Some waved Catalonian flags in solidarity with the independence protests in that region of Spain.

In contrast to previous demonstrations, tensions escalated quickly, with clashes erupting long before sunset. By late afternoon, protesters were throwing molotov cocktails and bricks at police stations.

In a show of their increasing sophistication, protesters also produced power tools to drill metal railings into road surfaces for sturdier barricades to hold back police.

Hong Kong authorities said protester violence has been escalating. In a statement released just after midnight, the government said police had intercepted a vehicle “with a large number of petrol bombs,” and “suspected explosive items” were found around the city. There were no reports that any explosives were detonated.

Hong Kong protesters hold Catalonian flags in solidarity with the independence movement in that region of Spain. (Philip Fong/AFP/Getty Images)

“Members of the public should not fall foul of the law by participating in unauthorised processions and assemblies in order not to give rioters the chance to commit crimes,” the government said.

The months of protests began in opposition to a bill that would have allowed extraditions to mainland China. The Hong Kong government said the legislation, since withdrawn, was in response to a brutal murder of a young Hong Kong woman by her boyfriend in Taiwan. He has since voluntarily surrendered to Taiwanese authorities, despite the lack of the extradition treaty.

Protests have swelled into a comprehensive rejection of Hong Kong’s leaders, who many say act only in Beijing’s interest, and revived a demand for direct elections in the semiautonomous territory.

“We don’t care whether they will approve the march or not. Our fight for justice in the face of tyranny goes on anyway,” said Victor, 24, who returned to his home city from New Zealand to participate in the protest. “The movement is spreading everywhere, all around the world.”

Sunday’s protest came days after the leader of the Civil Human Rights Front, Jimmy Sham, was attacked by a group of men wielding hammers in the Mong Kok neighborhood.

Protesters with umbrellas march through Hong Kong on Sunday. (Mark Schiefelbein/AP)

The beating left Sham, who is contesting a seat in next month’s local elections, splayed on the street and covered in blood. It was the second time in recent months that he had been targeted. He was released from the hospital on Sunday but will continue to need medical treatment and physical therapy.

“The message was clear that someone or some forces behind the scenes are trying to threaten protest organizers and democracy activists,” said Eric Lai, vice convener of the Civil Human Rights Front. “We cannot identify who was behind the attacks, but the objective is to create a chilling effect on those who are making demands for justice.”

The CHRF, founded in September 2002 in opposition to proposed national security legislation, is an umbrella organization made up of several civil society groups. While the protest movement has remained leaderless and largely decentralized, the group has played a major role in organizing the largest marches.

Online rumors that Sham’s attackers appeared to be South Asian prompted fears that ethnic minorities could be targeted for reprisal. In response, protesters called for greater outreach to non-Chinese Hong Kongers and to remain vigilant against attempts to incite violence against them.

A protester heaves a gas bomb toward Tsim Sha Tsui police station. (Ammar Awad/Reuters)

Volunteers, minorities, protesters and others stood at the gate to the Kowloon Mosque during the protest, holding signs pleading for people not to attack any ethnic minority people or buildings. While some handed out supplies, others led chants, and passing marchers loudly cheered them on.

But only a few hours later, a police truck unleashed a cascade of blue water at the mosque, hitting the people who had been guarding it. The blue dye is used to identify demonstrators.

Passersby were left choking and vomiting, and the steps of the mosque were stained blue. Phillip Khan, a prominent businessman in the Muslim community standing outside the mosque, called the act an “insult to Islam.”

“It is ridiculous. The police just went mad,” said Jeremy Tam, a pro-democracy lawmaker, his pants and shoes soaked blue and his eyes bloodshot. “We came here to protect the mosque against protesters, but it was the police that did this.

“Why make such a scene when it was just peaceful?”

Nawaz, a 36-year-old Pakistani man who has lived in Hong Kong for 25 years, emerged to see the blue-stained road after the cannon had sped past.

“I have such a bad feeling seeing this,” he said. “This is our religion. How can they do this? Only the police are giving us pressure, not the protesters.” Like others, he declined to give his family name for fear of backlash from authorities.

Police said in a statement later that the mosque was “accidentally affected” and they had “immediately contacted” the chief imam and Muslim community leaders to “clarify the situation and to show” concern.

On Monday, Chief Executive Carrie Lam and representatives from the police department toured the mosque. Both Lam and the police department have extended rare apologies for what they say was the “inadvertent” spraying of the mosque during the police operation.

“We certainly respect religious freedom in Hong Kong and will strive to protect all places of worship,” said Cheuk Hau-yip, regional commander of the Kowloon West area, where the mosque is located, as he reiterated the apology. “As the head of the Kowloon West Region, I would like to reiterate that we certainly do not have any malicious intent.”

Police representatives however continued to insist that a dangerous crowd was standing outside the mosque and the water cannon was to protect it.

Police arrive to chase away protesters. (Kin Cheung/AP)

Tense scenes unfolded outside the Tsim Sha Tsui police station by early afternoon, as protesters marching past shouted chants calling the police gangsters and demanding the force be dissolved. Police use of force has emerged as a key complaint for many in Hong Kong, who say officers are acting with impunity to suppress the movement.

A protester urinated on the station’s gates, and police fired tear gas to disperse the crowd. Tear gas streamed down the Ladies Market, a popular tourist attraction, sending unprotected stall-holders and shoppers scurrying for cover. Some were assisted by protesters and volunteer medics.

Many demonstrators, facing the possibility of being penned in by police, found sanctuary in little businesses that support the protests or huddled in overflowing restaurants, cafes and bars where they could change their clothes and wait for reports on Telegram indicating how they could get safely away while avoiding the police.

Sunday’s protest, planned initially to show opposition to a recently enacted law banning the use of face masks at public gatherings, continued for hours from a starting point in the Tsim Sha Tsui neighborhood. April, 27, and her boyfriend, William, 29, stood near a park where protesters first gathered. The couple said they had held off getting married or having kids out of concern over the direction of Hong Kong and the possibility of raising children in a city where Beijing’s grip is tightening.

“The situation for future generations is turning worse very quickly. We are really worried,” April said. “If we don’t fight today, there won’t be a future generation.”