Anti-government protesters are occupying Hong Kong Polytechnic University after retreating from the other campuses where they had held demonstrations last week. The ongoing confrontation with police has turned the school known as “Poly U” into a fiery battleground.

WHAT IS POLY U?

The public research institution that became fully accredited in 1994. It was established decades earlier as a trade school offering technical education. Today, it retains a focus on professional training, with programs in engineering, textiles and construction.

In this Monday, Nov. 18, 2019, photo, protesters go down the steps at the front entrance of Hong Kong Polytechnic University in Hong Kong in attempt to flee. The ongoing confrontation with police has turned the school known as “Poly U” into a fiery battleground. (AP PhotoRaf Wober)

In this Monday, Nov. 18, 2019, photo, protesters go down the steps at the front entrance of Hong Kong Polytechnic University in Hong Kong in attempt to flee. The ongoing confrontation with police has turned the school known as “Poly U” into a fiery battleground. (AP PhotoRaf Wober)

WHAT HAS BEEN HAPPENING THERE?

Protesters began occupying several campuses last week, including Hong Kong University and the Chinese University of Hong Kong, but have retreated from the others.

At Poly U, they set up barricades at major entrances and turned the school cafeteria into a “Confrontation Canteen,” outfitting one statue with the movement’s trademark hard hat and face mask.

FILE - In this Nov. 15, 2019, file photo, a protester rests near a statue of Sun Yat-sen, the father of modern China, at the Hong Kong Polytechnic University in Hong Kong. The ongoing confrontation with police has turned the school known as “Poly U” into a fiery battleground. At Poly U, they set up barricades at major entrances and turned the school cafeteria into a “Confrontation Canteen,” outfitting one statue with the movement’s trademark hard hat and face mask. (AP PhotoKin Cheung, File)

FILE - In this Nov. 15, 2019, file photo, a protester rests near a statue of Sun Yat-sen, the father of modern China, at the Hong Kong Polytechnic University in Hong Kong. The ongoing confrontation with police has turned the school known as “Poly U” into a fiery battleground. At Poly U, they set up barricades at major entrances and turned the school cafeteria into a “Confrontation Canteen,” outfitting one statue with the movement’s trademark hard hat and face mask. (AP PhotoKin Cheung, File)

Police advanced on the protesters Saturday night and battled with them over the next 24 hours, driving them off surrounding streets and into the campus.

Police set a cordon up around the area late Sunday, warning that those inside would be arrested. Many have come out, some younger students escorted by parents and principals, while others have tried to evade the cordon and escape. About 100 are believed to remain.

WHY WAS IT CHOSEN?

FILE - In this Nov. 17, 2019, file photo, a protester stands on a bridge near the Hong Kong Polytechnic University in Hong Kong. Anti-government protesters are occupying Hong Kong Polytechnic University after retreating from the other campuses where they had held demonstrations last week. The ongoing confrontation with police has turned the school known as “Poly U” into a fiery battleground. (AP PhotoVincent Yu, File)

FILE - In this Nov. 17, 2019, file photo, a protester stands on a bridge near the Hong Kong Polytechnic University in Hong Kong. Anti-government protesters are occupying Hong Kong Polytechnic University after retreating from the other campuses where they had held demonstrations last week. The ongoing confrontation with police has turned the school known as “Poly U” into a fiery battleground. (AP PhotoVincent Yu, File)

Polytechnic offered a strategic confluence point as protesters sought to block major roads and disrupt train service to force the city into a “general strike.”

Using Polytechnic as a base, demonstrators were able to block off the nearby Cross-Harbour Tunnel, one of three main road connections under the harbor to Hong Kong Island, as well as major roads such as Chatham Road South.

The symbolism of taking over university campuses also appealed to some protesters who say they’re fighting for freedom and independent thought.

WHAT’S THE CURRENT SITUATION?

As of Tuesday morning, about 600 protesters had left the campus, according to Hong Kong leader Carrie Lam. About 400 of them have been arrested.

In a bid to encourage protesters to leave, police are not immediately arresting those under 18. Minors are instead having their details recorded and could be charged later.

Associated Press writer Yanan Wang in Beijing contributed to this report.