HONG KONG (NYTIMES) - The police returned control of Hong Kong Polytechnic University’s campus to school officials on Friday (Nov 29), bringing to an end one of the most intense periods of conflict since protests began to engulf the city in June.

The police, who arrested hundreds of people during their two-week siege of the campus, said they found no protesters there during a final search on Friday morning.

Investigators found nearly 4,000 firebombs on the campus over the past two days, as well as other explosive items and bottles of corrosive liquids, the police said.

The siege, which was punctuated by days of clashes between the police and protesters, ended quietly as university officials resumed control of the shattered campus on the southeastern side of the Kowloon Peninsula.

There will not be “any ceremony or event to shake hands or stuff like that”, assistant police commissioner Chow Yat-ming said on Friday morning before officers left the campus.

The protests began in June over legislation, since withdrawn, that would have allowed the extradition of criminal suspects to mainland China.

The protests have continued over other issues, including calls for expanded elections and an investigation into the police’s use of force.

Hong Kong universities became the centres of especially large protests this month after the death of a student, Mr Chow Tsz-lok, who fell from a parking garage during a police operation.

The Chinese University of Hong Kong was occupied by protesters for five days in mid-November, and several other schools saw large demonstrations.

Many campuses cut their semesters short because of the unrest.

At Polytechnic University, students who took up their protest there on Nov 11 were later joined by militant demonstrators who were determined to keep the police out, fortifying their position with firebombs, bricks and large slingshots.

On Nov 17, the police threatened to use lethal force against the demonstrators and warned that those caught could be charged with rioting, which can carry a lengthy prison sentence.

Protesters also set fire to tollbooths near the campus, leading to the two-week closure of a major tunnel linking the Kowloon Peninsula with Hong Kong Island.

The police said more than 5,800 people had been arrested in connection with the protests since early June, including nearly 1,500 people over the past two weeks.

Polytechnic University and the streets around it saw large-scale clashes between riot police officers and protesters who were trying to help others flee the besieged campus.

The police fired more than 1,400 tear gas rounds on Nov 18 alone, as large numbers of protesters tried to break through the police cordon around the school.

Protesters hurled bricks and firebombs at the police, and at one point an armoured police vehicle was engulfed in flames.

One officer was hit in the leg with an arrow.

Some protesters managed to escape the campus by jumping fences when the police were not watching.

In one dramatic moment, a few rappelled onto a roadway and were taken away by people on motorcycles.

Others tried but failed to escape through sewers.

The police detained about 1,100 people near the campus on Nov 18 and 19.

The protests in Hong Kong quieted dramatically in the days before Sunday, when elections were held for district councils across the city.

Pro-democracy candidates dominated the vote, which had been seen as a referendum on the protest movement, taking 87 per cent of the seats.

On Wednesday, President Donald Trump signed legislation that authorised sanctions on officials deemed responsible for human rights violations in Hong Kong.

Demonstrators in Hong Kong celebrated that legislation with a peaceful gathering on Thursday night.