Protesters demanding the resignation of Hong Kong’s chief executive have clashed with riot police in a mainland shopping centre in Sha Tin.
Footage shows officers appearing to strike demonstrators with batons after more than 10,000 people marched for greater democracy in the territory.
Protesters also called for an investigation into complaints of police violence.
The demonstrations that began at around 3pm in the northern Hong Kong district of Sha Tin were peaceful throughout most of the day.
Scuffles broke out after nightfall when police started clearing the streets in the densely-crowded area of high-rise buildings.
Hundreds of protesters wore helmets and surgical masks as protection against possible police use of pepper spray or tear gas.
The demonstrators retreated into a shopping complex where some threw umbrellas and water bottles at police.
The two sides were later seen along the walkways of several floors of the complex hitting each other with umbrellas and grabbing each other’s helmets.
Major protests have taken place in the last month against a proposal to change extradition laws in Hong Kong, which would allow crime suspects in the territory to be transferred to the mainland.
The demonstrations have swelled to include complaints about an influx of mainland Chinese to the territory, and claims local leaders are more response to the Beijing government than to the territory’s people.
Protesters demanded an investigation on Sunday into complaints police assaulted participants in demonstrations against the proposed extradition law change.
Some carried signs reading “Police Are Liars”.
Other signs read “Defend Hong Kong”.
Hong Kong’s Chief Executive Carrie Lam suspended action on the extradition bill last month.
Ms Lam apologised for her handling of the legislation but critics are demanding she resign.
Police used clubs and tear gas to break up a crowd of mostly young protesters who called for tighter control on mainland traders who visit Hong Kong on Saturday.
Critics say they are improperly undercutting Hong Kong businesses.