Hong Kong police have fired teargas and for the first time used a water cannon to disperse protesters as a weekend of violent clashes dashed hopes of a return to peace after a week of relative calm.

Hundreds of thousands of people had earlier braved rain on Sunday to stage a peaceful, police-sanctioned march in Tsuen Wan, an area of the city noted for its links with triad gangsters, after clashes on Saturday when police fired teargas, rubber bullets, pepper balls and sponge rounds at protesters.

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By late afternoon on Sunday, about 100 riot police officers had formed into lines on two streets and protesters began to build makeshift barricades with plastic traffic barriers and bamboo rods in a standoff between the two sides. Just after 5.30pm local time police fired several rounds of teargas.

The crowd largely stayed put behind the barricades in the midst of choking smoke and some threw gas canisters back at the police. Protesters also threw bricks and Molotov cocktails at the police, with flames seen on the road between the two sides.

Minutes later, police launched another volley of teargas and charged at the protesters as the crowd dispersed. For the first time, police also used two anti-riot vehicles equipped with water cannons to chase away protesters.

Facebook Twitter Pinterest A police vehicle equipped with a water cannon clears the road at a barricade set up by protesters. Photograph: Jérôme Favre/EPA

After the dispersal, protesters in small groups spread to several districts across the city late into the night, causing disruptions as they led the police in a game of cat and mouse.

A group of protesters shone laser beams into the Sham Shui Po police station, before riot police arrested at least four of them, reported the public broadcaster RTHK. At Tsim Sha Tsui, an area popular with tourists, some set up barricades on the main thoroughfare with rubbish bins and a small fire was lit in bushes outside a police station, according to local media.

Protesters also targeted a cross-harbour tunnel briefly late at night, using barriers to partially block traffic and sticks to smash lights, security cameras, and toll booth windows at an entrance. They fled after about 10 minutes, according to RTHK.

In Tsuen Wan, an area with a high proportion of low-income mainland migrants and links to triad gangsters, where protesters had previously been attacked, a dozen men wielding metal poles and clad in white and blue tops appeared in the area, with some holding the Chinese national flag. They dispersed shortly after riot police intercepted.

Police in Tsuen Wan also fired warning shots into the air after officers who charged at protesters were attacked with metal and bamboo poles and pointed their guns at a group of people including journalists, RTHK reported.

The Hong Kong government said in a statement on Monday that it “severely condemns” the protesters. “The escalating illegal and violent acts of radical protesters are not only outrageous, they also push Hong Kong to the verge of a very dangerous situation.” It said police would “strictly follow up” on those acts.

In a separate statement, police said they arrested 36 people on Sunday, aged 12 to 48, for unlawful assembly, possession of offensive weapon and assaulting police officers.

After almost three months of continuous protests, demonstrators said remained determined in their fight for political rights. They swore to continue their struggle as long as the government refused to heed their political demands.

Facebook Twitter Pinterest Demonstrators stand behind barricades, surrounded by teargas. Photograph: Kai Pfaffenbach/Reuters

“The more the government ignores us, the more we have to come out,” said Peggy Tai, who is in her 60s, earlier in the day.

The wave of protests, which started in early June to oppose an extradition bill under which individuals could be sent to mainland China for trial, has morphed into a broader anti-government movement.

Demonstrators have five demands: the complete withdrawal of the now-suspended extradition bill; the setting up of an independent body to investigate police violence; a halt to the characterisation of protests as “riots”; an amnesty for those arrested; and a resumption of political reform to allow the free election of Hong Kong’s leader and legislature.

Hong Kong’s leader, Carrie Lam, said earlier in the week that she would establish platforms for dialogue although protesters dismissed her offer and said she needed to respond to their demands.

Police said 29 people were arrested on Saturday for unlawful assembly, possession of offensive weapons and assaulting police officers following the violent clashes, including Ventus Lau, the organiser of the peaceful march earlier in the day.

“I fear less about being arrested than Hong Kong being stripped of our rights and freedom,” said a protester who identified himself as Rock. “We were wrong to stop fighting after the umbrella movement five years ago and so much has been taken away from us since. This time, we’re more determined.”

This weekend’s violent confrontations took place after more than a week of mostly peaceful demonstrations in the semi-autonomous city. Last weekend there were the first teargas-free protests after organisers called for events to be peaceful and non-violent. A rally at Yuen Long station on Wednesday turned into a tense standoff between police and protesters but ended without violence. Another rally in the form of a human chain that stretched for kilometres on Friday also ended without incident.

Activists have also planned a city-wide strike, a sit-in outside the tax office, a small scale rally in the central business district and a large protest next Saturday as well as class boycotts at universities and schools in coming weeks.