Petrol bombs were thrown and tear gas fired as protests in Hong Kong turned violent.
It came after thousands had marched in downtown Hong Kong amid heavy rain on Saturday.
It was the latest demonstration in a series of pro-democracy protests that have plunged the Chinese-ruled city into its worst political crisis in decades.
People took to the streets despite police attempts to block any large protests.
Demonstrators are marking five years since a Chinese government ruling effectively gave Beijing control over the candidates for Hong Kong's next leadership election.
Police arrested a number of prominent pro-democracy activists and three lawmakers on Friday, seeking to rein in a movement which started with anger over planned legislation allowing extraditions to mainland China. It soon broadened into calls for democracy amid fears China is squeezing Hong Kong's freedoms.