Sporting their movement's trademark black clothing and face masks, rally participants packed into Chater Garden, not far from the city's Legislative Council building. They held up signs that read "Free Hong Kong" and waved American and British flags.
A former British colony, Hong Kong was returned to China in 1997. While the framework of "one country, two systems" promises the territory greater democratic rights than are afforded to the mainland, protesters say their freedoms have been steadily eroding under Chinese President Xi Jinping.
Frictions between democracy-minded Hong Kongers and the Communist Party-ruled central government in Beijing came to a head last June, when proposed extradition legislation sparked months of often violent mass demonstrations.
The bill — which would have allowed Hong Kong residents to be sent to mainland China to stand trial — has since been withdrawn, but protests have continued for more than seven months, centered around demands for voting rights and an independent inquiry into police conduct.
Hong Kong police gave approval for Sunday's rally, but not for a march that organizers also are planning.
Protesters ran for cover after riot police appeared around the park and raised yellow warning flags, telling the crowd that they should disperse because they were participating in an illegal assembly.