The tens of thousands of protesters began their illegal march equipped with banners and umbrellas from Salisbury Garden in the shopping district of Tsim Sha Tsui toward the West Kowloon terminus of the high-speed rail link, which was heavily guarded by police.

But before long, the protesters headed north all the way to Sham Shui Po along Canton Road and Nathan Road, as radicals forced open the shutters of shops and banks with mainland links and began trashing them and setting fires to several of them, including a Bank of China outlet.

Apart from the branches of Best Mart 360 — which had been target of vandalism after being accused of having ties with the “Fujian gangs” that had allegedly beaten protesters in the past — the Mong Kok branch of Chinese medicine group Tong Ren Tang was also smashed and its medicine cabinets ransacked. Protesters later returned to the medicine store to set it on fire.

In Yau Ma Tei, an elderly man who was accused of stealing at least three mobile phones from a trashed Xiaomi store was tied up by protesters who insisted they did not condone looting.

A tense stand-off also erupted near the Park Lane Shoppers’ Boulevard as protesters repeatedly hurled petrol bombs at the Tsim Sha Tsui station as officers fired rounds of tear gas at them from inside.

Protesters cut down a surveillance camera near a Yau Ma Tei MTR exit with an electric chainsaw, before setting it on fire. They then threw petrol bombs inside at least four metro stations through their closed exits — forcing the partial suspension of Tsuen Wan line and the closure of at least 14 stations. The city’s railway operator MTR has been the target of protesters who accused the operator of aiding the police’s clearance actions.

By evening, a bomb disposal robot — believed to be deployed for the first time during the four-month protests — had also detonated a suspected explosive device inside a cardboard box placed at the intersection of Lai Chi Kok Road and Tong Mi Road in Tai Kok Tsui. The marauding protesters also set a traffic light controller ablaze, apart from the fires they started in the shops the broke into.

In Mong Kok, riot police fired tear gas and rubber bullets at the mob but later appeared uncertain whether to continue their actions. As they retreated, protesters threw bricks at their vehicles, breaking the windows. Police then returned to clash again with the mob, before retreating yet again.

Figo Chan Ho-wun, the vice-convenor of the front who pushed ahead the banned march alongside three pan-democrats in their personal capacity, claimed an estimated 350,000 people had taken part in it.

A 25-year old frontline protester, surnamed Tang, said protesters had resorted to more violent behavior because peaceful protests had not worked.

“Carrie Lam Cheng Yuet-ngor just won’t listen,” the banking staffer said, referring to the city’s chief. “We must continue with our fight.”

The police force condemned the mob, as it urged passers-by to stay away from the scenes of chaos.

“Fires set by rioters seriously affect personal safety of members of the public. Indoor fires can quickly get out of control and burn residents living above the shops,” the statement read.

Police also said two men, aged 31 and 34, were arrested for “possession of an offensive weapon” in Tai Po and on suspicion of “supplying weapons” to protesters in Kowloon on Sunday. Weapons including 42 suspected petrol bombs and raw materials for creating paintballs were found in two vehicles — a taxi and a seven-seater car — during a search.

In a statement released just before midnight, the Hong Kong government strongly condemned the acts of “rioters who completely disregard law and order.”

Meanwhile, the city’s embattled leader Lam is set to leave for Japan on Monday to attend the enthronement ceremony of Emperor Naruhito to be held the next day. She is expected to return on Tuesday.

Reporting by Phila Siu, Linda Lew, Kimmy Chung, Karen Zhang, Karen Yeung and Jeffie Lam