Hong Kong police have ordered the last remaining knot of demonstrators to leave the city’s main protest site after a deadline for the crowds to disperse passed.

Authorities on Thursday began dismantling barriers and breaking up rallies in the final showdown of a protest that has lasted two-and-a-half months and lead to 655 arrests.

Police said to protesters holding a sit-in they would use “minimal force” if the group did not stand up and leave voluntarily.

They then began taking away protesters from the sit-in next to government head quarters. Protesters were allowing themselves to be taken away without putting up resistance said Al Jazeera’s Divya Gopalan, reporting from Hong Kong.

Protesters were shouting “can you face the next generation” as they were taken away, our correspondent said.

Politicians and lawyers were among those arrested.

Police had previously created an exit route to allow people to leave the site, but those doing so had to present their identification first.

“The atmosphere is charged but the protesters are waiting for what happens next with an almost zen like appearance,” Gopalan said.

“The older generation are stepping in now, telling the younger protesters to leave and take care of themselves. The older protesters say it is their turn to pick up the mantle and face the music.”

Human rights monitors told Al Jazeera that the proceedings were being carefully observed.

“Police are treading carefully as they inch towards the other end [of the site] near Wanchai, dismantling tents and slowly moving towards the art area including the mock coffin of the chief executive,” Gopalan said.

Bailiffs had already moved in to remove barricades around the protest camp in the heart of the business district, but despite the police order, a hard core of a few hundred refused to leave.

Crowds shouted demands for free leadership elections, a cause which has underpinned the demonstrations, and vowed the clearance operation would not end a campaign they say has redefined the city’s vexed relationship with Beijing.

Police announced a “lockdown” of the area after a 30-minute window in which protesters could voluntarily leave the site, an encampment of tents, supply stations and art installations sprawling along a kilometre of multi-lane highway.

“Police will lock down the occupied area and set up a police cordon area… If anyone refuses to leave police will take action to disperse or arrest,” said police superintendent Kwok Pak-chung.

Al Jazeera’s Sarah Clarke, reporting from the scene on Thursday morning, said police entered from two different sides while some protesters packed up their tents and moved away.

“[These protests] have changed Hong Kong for good, but there has been no compromise from Beijing. Where we go from here is what every one will be watching,” our correspondent said.

Thousands had gathered on Wednesday night for one final mass rally at the Admiralty site, but the numbers had dwindled by morning, leaving just a few hundred sitting in the road, including politicians who describe themselves as pro-democracy.

Student protest leaders vowed to stay put until the last minute and peacefully resist a police operation.

“If the government wants to use police to clear the site, don’t forget, the clearance can’t resolve political conflicts, it can’t resolve society’s dilemma,” said Joshua Wong, the 18-year-old head of the Scholarism group and the protest movement’s most prominent leader.

Close scrutiny

Pak-chung warned the public that anyone obstructing the bailiffs would be arrested.

The police operation will be under close scrutiny with a group of about 30 academics monitoring the operation, along with the Independent Police Complaints Council and human rights groups.

The sprawling encampment in Hong Kong’s Admiralty section, on the edge of the financial district, has been the focal point for the protesters, who have occupied the site for 75 days.

Police now say they will meet their target of allowing traffic flow to resume in the area by midnight on Thursday, after months of protest sites restricting movement in the area.

The mainly peaceful protests have represented the most serious challenge to China’s authority since the 1989 pro-democracy demonstrations and bloody crackdown in and around Beijing’s Tiananmen Square. Al Jazeera