Seven Hong Kong pro-democracy lawmakers have been detained or face arrest as thousands gathered at a Christian memorial service for a student who died after a fall.
Protesters vented their anger over Chow Tsz-Lok's death and vowed not to give up their resistance at a police-approved prayer rally on Saturday night, with frequent chants of "Hong Kong people, revenge" and "Free Hong Kong".
Mourners sang hymns and laid white flowers and paper cranes at a makeshift stage in a downtown park.
The 22-year-old died on Friday, succumbing to injuries four days after falling from a parking garage when police fired tear gas during clashes with protesters.
Although the circumstances of his death are unclear, many blame police who have been accused of heavy-handed tactics including widespread use of tear gas and pepper spray since the unrest began in June.
It wasn't clear what Chow was doing at the garage early on Monday as mobs clashed with police in the streets below. Police have repeatedly denied that officers pushed him down and had delayed emergency services and treatment.
At the evening prayer rally, various speakers, including hardline protesters, took to the stage to call for justice for Chow and vowed never to surrender.
"Hong Kong people can be struck down but never defeated," said a masked black-clad protester. Another protester urged citizens to show their anger by going out early to vote in the district council elections.
Prominent activist Joshua Wong, who has been barred from running in this month's polls, said the city can emerge from the chaos if protesters unite and fight on despite the tough road ahead.
There have been only a few fatalities during the unrest, including some reported deaths by suicide and a man who fell to his death while hanging pro-democracy banners on a building.
Meanwhile police said three lawmakers were detained on Saturday and charged with obstructing the local assembly during a raucous May 11 meeting over the now-shelved China extradition bill that sparked five months of protests calling for democratic reforms.
The others received summons to turn up at police stations on Saturday to face arrest. All seven are to appear in court on Monday.
Pro-democracy lawmakers slammed the government clampdown as a calculated move after Chow's death to provoke more violence as an excuse to postpone or cancel November 24 district elections - polls viewed as a barometer of public sentiment amid the unrest.
"We'll say no to their plans," lawmaker Tanya Chan told a news conference. "It is a de facto referendum for all Hong Kong voters to cast their vote and say no to police brutality and say no to our unjust system."
She said the district elections will also send a crucial message to Beijing, accused by protesters of interfering in the city's freedoms and rights promised when the former British colony returned to Chinese control in 1997.
Hong Kong's constitutional and mainland affairs secretary, Patrick Nip, said police made the arrests based on their investigation and that they had nothing to do with the upcoming elections.