Protesters yesterday showed their unhappiness with the government for ignoring their demands by surrounding the police headquarters, the Legislative Council complex and government offices.
The blockade effectively paralysed traffic and forced government offices to close.
They had set a 5pm deadline on Thursday for the government to formally withdraw a contentious extradition Bill that was suspended after last week's massive rallies, some of which ended in clashes between protesters and the police.
They have also demanded that the police retract their characterisation of the protests as a riot, that all charges against those arrested be dropped and that an investigation be held into what critics say was excessive use of force by the police.
Yesterday, protesters clad in black and wearing masks used police crowd control barriers to prevent staff from entering the police headquarters in Wan Chai, while others blocked off major roads nearby and in Admiralty using concrete barriers and metal fences.
Chanting "Release the people" and "Police, disgrace", the protesters alternated between cheers and boos as they also demanded a meeting with Police Commissioner Stephen Lo. Some in the crowd threw eggs at the police headquarters building.
Fears of being identified led some to block closed-circuit television cameras with umbrellas and duct tape, and to shout at journalists not to take photographs. A patrol car surrounded by the crowd was immobilised for some three hours.
The crowd swelled in the evening, turning roads into a sea of black as they faced off against police officers armed with riot shields.
The government, in a statement in the evening, called on protesters to express their views "peacefully and with reason", adding that work on the Bill has been suspended.
Senior Superintendent Yolanda Yu of the police public relations branch said negotiation experts tried to persuade the protesters to leave, but their attempts were met with jeers. The police said the blockade prevented officers from attending to emergency calls.
Law enforcement officials put out a video of their version of the events, saying the blockade was planned and organised.
In the afternoon, hundreds of protesters briefly blocked the lobbies of the Inland Revenue and Immigration department buildings, but were less successful when trying to occupy the main government offices, which had been closed in anticipation of the protests.
Hong Kong Chief Executive Carrie Lam, who had apologised twice over her handling of the extradition Bill after last week's massive rallies, has not responded to the protesters' latest moves.
"Why is she keeping quiet?" asked student Kenneth Lau, 16, who added that he and his friends will do "whatever it takes" until they get an answer from Mrs Lam.
Amnesty International yesterday said it collected footage and verified 20 of them concerning 14 incidents of excessive use of force by police officers on the ground.
Secretary for Justice Teresa Cheng yesterday became the third official to apologise for the government's missteps, after Mrs Lam and Secretary for Security John Lee.
"We promise to adopt a most sincere and humble attitude to accept criticisms and make improvements in serving the public," she said in a statement.
Public anger has been mounting since the Bill was mooted in February. If passed, it would allow extraditions to jurisdictions including mainland China. Hong Kongers fear that those sent to the mainland will not receive a fair trial or human rights protection.