The demonstrations have been ongoing for five months now, and Sunday's turnout was a test of the movement's strength.
Just a day earlier, several hundred people, some waving USA flags, rallied peacefully at Edinburg Place in Central, calling on the global community for help in what they described as a humanitarian crisis engulfing the city, reported RTHK. HKMap's developers, however, said there hasn't been any evidence to suggest their app had been used to target police and undermine public safety.
Police had beefed up security measures for the unauthorised rally, the latest in the 5-month-old unrest rocking the semi-autonomous Chinese city. A prominent human rights activist, Jimmy Sham, was attacked by men with knives this earlier this week, an attack pro-democracy lawmakers say was created to intimidate protesters.
Banks, automated teller machines, a bookstore and shops with perceived links to China as well as traffic lights and subway stations along Nathan Road were vandalized.
Chan's case was one of the main reasons that Lam wanted to pass the proposed extradition amendments.
They also wrote separately to Activision to reconsider its decision to suspend a Hong Kong gamer after he voiced support for the protesters during an interview.
Sunday's march was banned by the police despite organisers' pledge to keep it peaceful and non-violent.
Protesters have targeted Chinese banks and shops with links to mainland China, leaving mainland Chinese living in Hong Kong anxious about their safety.
"We don't think that because police haven't given their approval we shouldn't demonstrate", Figo Chan, vice-convener of the Civil Human Rights Front, said.
HKMap.live, which has been "widely used" by Hong Kong protesters to locate where police forces are deployed, is not the only app that Apple has "censored", the U.S. lawmakers claimed in their letter.
Supporters sang the protest movement's anthem, waved colonial and US flags, and held up placards depicting the Chinese flag as a Nazi swastika.
"You can see Hong Kongers won't easily give up their right to demonstrate".
"While we always respect citizens' rights to assembly and freedom of speech, we are alarmed by this epidemic that radical protesters resort to violence in expressing their opinion", Acting Chief Superintendent of Police Public Relations Branch, Kong Wing-cheung, said in announcing the rejection.
Supporters are holding a prayer rally on Saturday night. But they morphed into wider calls for democracy and police accountability after Beijing and local leaders took a hard line.
The protest movement sprang out of opposition to a government proposal for an extradition bill that would have sent suspects to mainland China to stand trial, and then ballooned into broader demands for full democracy and an inquiry into alleged police brutality.
Clashes broke out as tens of thousands took to the streets for an unsanctioned anti-government march, many also defying a face mask ban introduced in a bid to curb the protests. Austin, Mong Kok, East Tsim Sha Tsui, and Yau Ma Tei were among those affected.