What had been a peaceful march to press authorities for more concessions after more than half a year of protests, deteriorated into tense scenes mid-way during the march, with police firing tear gas to disperse protesters in the Wanchai district.
Frontline protesters quickly formed a line of defence, and some hurled petrol bombs back at police, according to Reuters reporters on the ground.
Hong Kong has been embroiled in more than six months of anti-government protests that have now spilled into 2020, with protesters demands including full democracy and an independent inquiry into allegations of police brutality.