0132 GMT December 06, 2019
Sunday's demonstrations came after brief skirmishes erupted overnight following the November 24 district council elections that saw pro-autonomy candidates win a landslide, AFP reported.
Police fired tear gas and pepper spray in Hong Kong as tens of thousands of black-clad protesters flooded into the streets.
Police have issued permits called "letters of no objection" for the Sunday events, including a morning rally for children and seniors which went ahead without incident, and the post urged people to remain peaceful.
"I want to beg everyone to remain highly restrained during the hours covered by the letter of no objection. Otherwise I could be charged with inciting riots," organizers wrote in the anonymously penned post.
On Saturday night, police fired three rounds of tear gas for the first time since the elections, after protesters blocked roads in the Mong Kok neighborhood.
Police have fired more than 12,000 tear gas canisters since the protests began, with gas masks becoming a must-have for those attending demonstrations but often a cause for arrest if discovered.
A video that emerged online also showed a protester brutally assaulting a man as he attempted to clear a barricade.
The commentator mocks the man, who stumbles and then slumps over after being hit across the head with a heavy metal object, blood trickling from a wound.
In a radio interview on Sunday morning, police chief Tang Ping-keung said an attack took place in Mong Kok.
"It could have killed him," Tang said.
A police source confirmed that the incident seen in the video occurred in Mong Kok on Saturday night and that it was under investigation.
The condition of the man was not immediately clear. But hospital authorities said three people were brought in on Saturday night with protest-related injuries, one of whom was discharged while the other two were in a stable condition.
Protests erupted in Hong Kong nearly six months ago in opposition to a bill that would have allowed extraditions to mainland China.
The bill has been withdrawn, but the movement has snowballed into wider calls to protect the city's freedoms.