HONG KONG — Thousands of demonstrators again blocked main city thoroughfares on Friday and, in a new show of displeasure, surrounded police headquarters, demanding that a deeply unpopular extradition bill be fully withdrawn by the city’s leader and that police investigate cases of alleged police brutality.

For more than a week, enormous numbers of protesters have taken to the streets of the semiautonomous territory, calling for the scrapping of a bill that would allow for extraditions to China. The continued upheaval has placed Carrie Lam, the pro-Beijing chief executive, at the center of the most serious crisis of her political career.

Lam has suspended the bill and offered up two public apologies but has refused to withdraw the legislation completely. Her apologies have been dismissed as self-serving, and many continue to demand that she resign.

Some government offices downtown were closed Friday in anticipation of the rallies.

Friday’s protests were originally organized, in part, by the student unions of Hong Kong universities but gathered support online and through messaging apps popular with younger demonstrators. Student leaders had given the government until 5 p.m. local time on Thursday to respond to a list of four demands or face new protests.

In addition to seeking the withdrawal of the bill and a police misconduct investigation, they also want charges against those arrested during past protests to be dropped and the retraction of references to the June 12 protest as a “riot.”

So Tsun-Fung, the president of the student union of the Chinese University of Hong Kong, said students were disappointed and angered by the government’s response. “We need to put more pressure on the government,” he said.

Although some have questioned the wisdom of the latest protest, which comes less than a week after an estimated 2 million people took to the streets, So said they needed to maintain momentum. “If we wait, it will be too late,” he said.

Harcourt Road, a major motorway through Hong Kong’s central district, has been a focus of past demonstrations, including last week’s occupation that ended with police firing tear gas and rubber bullets at protesters.

On Friday, protesters again blocked the road, though the crowds were thinner than during previous closures. After speaking out on Lam, demonstrators are now directing their anger toward the police. In recent days, videos of officers arresting protesters and firing tear gas have been shared widely on social media, eliciting outrage.

Outside police headquarters, protesters pelted officers with eggs, which splattered on police riot shields.

Artwork depicting the police violently confronting protesters has popped up around the city, as have groups projecting videos of the incidents onto screens in public.

Sonia, 18, who spoke on the condition that only her first name be used, said she was frustrated with police dismissing the complaints of young people and telling them to submit their grievances by email.

“We are all very angry about it,” she said. “The people who the police hurt are young people and students. They are vulnerable citizens.”

Like many in attendance, she had obscured her face with a dental mask.

Another protester, who spoke on the condition of anonymity to talk freely, said that while she understood police had a job to do, they acted in a “totally unreasonable” manner dispersing crowds on June 12. She cited a widely shared video showing a demonstrator being roughly apprehended by a group of about six officers.

Protesters taped photos of police firing tear gas and injured demonstrators to the police complex. Others blocked a police van in the road and pushed metal barricades against some doors to the building. A small group of protesters scaled the walls surrounding the police headquarters to cover surveillance cameras with tape or block them with opened umbrellas. 

With temperatures in the high 80s and stifling humidity, many took refuge in the shade of underpasses and stuck cooling patches to their foreheads. Officers stood in a line blocking the front door. One officer filmed protesters with a handheld camera.

The Hong Kong Police Force, which has previously defended its actions, said in a post on Twitter that the gathering would “seriously affect the emergency services provided by police.”

“Police now appeal to protesters to express their views in a peaceful and rational manner and stay safe,” it said.

The police force added in a statement Friday afternoon that it could not respond to about two dozen calls to the 999 emergency hotline because of the large crowd blocking roads. 

Joshua Wong, who rose to prominence as a leader of the 2014 Umbrella Movement and was just released from prison, addressed the crowd and called for Police Commissioner Stephen Lo to meet with protesters to hear their grievances.

Wong was absent from the mass demonstrations of the past month because he was serving a jail term for charges stemming from the 2014 protests, during which demonstrators paralyzed major roads in a 79-day occupation of central Hong Kong calling for universal voting to pick Hong Kong’s leaders.

Demonstrators also deployed a new disruptive tactic of targeting government institutions, swarming the buildings where offices are located. Faced with gathering crowds, supervisors let their workers leave early. “I think it is a better way,” said a 23-year-old protester who spoke on the condition of anonymity. “We stopped three or four government departments from working. They gave up and just let their workers leave.”