A sea of black coursed through Hong Kong’s skyscraper-lined streets on Sunday as an estimated two million protesters marched to demand chief executive Carrie Lam withdraw a contentious extradition Bill and resign immediately.

Organisers of the march, the Civil Human Rights Front said “almost” two million people took part in the protest. The territory has a population of 7.4 million in total.

In a dramatic about-face on Saturday, a contrite Mrs Lam expressed “sorrow and regret” that she had failed to convince the public the Bill was needed, and announced that in a bid to prevent further violence she would be suspending the proposed legislation indefinitely.

A statement from her office released on Sunday night said that “admitted deficiencies in the government’s work” had caused the controversy, and Mrs Lam “apologised to the people of Hong Kong for this and pledged to adopt a most sincere and humble attitude” moving forward.

Nevertheless, protest leaders urged Hong Kongers to come out on to the streets to demand Mrs Lam first fully withdraw the Bill and then resign.

In an incident that added grave intensity to the march, a 35-year-old protester fell to his death on Saturday after hanging a banner from a building where the main clashes took place saying “Make Love. No Shoot”, “No Extradition to China” and “We were not rioting. Release students and the injured.” The man had been clinging to scaffolding for some time and firefighters had placed a large inflated mattress beneath him in the hope of catching his fall, but as rescuers approached him he plunged to his death. Police say they are treating the case as a suicide, adding that he had left a note.

There were so many thronged into the parade starting point Victoria Park that the tail of the march only left the park more than seven hours after it began. The march was overwhelmingly peaceful, with a very low-profile police presence. Some marchers carried signs reminding people not to leave any litter behind. Under the “one country, two systems” principle, Hong Kong was guaranteed that it would be allowed a large degree of autonomy and permitted to retain its own social, legal and political system for 50 years after the handover from Britain to China in 1997. The protesters believe that Beijing has clearly reneged on that agreement.

Attempting to push the Bill through in the face of widespread opposition has revitalised the beleaguered pro-democracy movement and handed the government one of its toughest tests since the handover.

The protests are enjoying support from a wide cross-section of society, including businesspeople, lawyers, academics and religious groups.

Labour unions, teachers and student associations, and other groups are calling for a general strike and class boycott on Monday to add pressure on the administration to quash the proposed legislation.