About 100 anti-government protesters remained holed up at a Hong Kong university on Tuesday, unsure what to do next as food supplies dwindled and a police siege of the campus entered its third day.

City leader Carrie Lam said 600 people had left the Hong Kong Polytechnic campus, including 200 who are under 18 years old.

Police have surrounded the university and are arresting anyone who leaves. Groups of protesters made several attempts to escape on Monday, including sliding down hoses to waiting motorcycles, but it wasn’t clear if they evaded arrest.

Lam said those under 18 would not be immediately arrested but could face charges later. She said the other 400 who have left have been arrested.

“We will use whatever means to continue to persuade and arrange for these remaining protesters to leave the campus as soon as possible so that this whole operation could end in a peaceful manner,” she said after a weekly meeting with advisers.

After five months, the Hong Kong protest movement has steadily intensified as local and Beijing authorities harden their positions and refuse to make concessions. China took control of the former British colony in 1997 promising to let it retain considerable autonomy, but the protest movement was fueled by the belief those freedoms are being eroded.

Universities became the latest battleground last week, as protesters occupied several campuses, using gasoline bombs and bows and arrows to fend off riot police backed by armored cars and water cannon. Those at Polytechnic are the last holdouts.

One protester, who would not appear on camera, said he had no plan and is waiting for someone to come to help. Another said he wants to leave safely but without being charged. They would not give their full names out of fear of arrest.

Protesters milled about in small groups. Family members and teachers arrived sporadically to pick up those under 18, hugging their children before walking back to a police checkpoint, where officers recorded names and other information before letting them go.

The Japanese government said one of its citizens had been arrested near the Polytechnic campus. Japanese media identified him as Hikaru Ida, a student at Tokyo University of Agriculture. Officials did not say why he was arrested.

Hong Kong also got a new police chief, Chris Tang, who said rebutting accusations against police that he called “fake news” and reassuring the public about the force’s mission would be among his priorities.

“We have to maintain the law and order in Hong Kong and there is a massive scale of breaking of law in Hong Kong and there is a certain sector of the community that also condones those illegal activities,” he told journalists. Tang replaces a retiring chief and was selected by Beijing after being nominated by Lam’s government.

Lam, asked whether she would seek help from Chinese troops based in Hong Kong, said her government remains confident it is able to cope with the situation.

China hinted it might overrule the Hong Kong’s High Court ruling on Monday to strike down a ban on face masks that was aimed at preventing protesters from hiding their identity to evade arrest.

A statement from the National People’s Congress’ Legislative Affairs Commission said the decision doesn’t conform with territory’s constitution, known as the Basic Law, or decisions by the Congress.

“We are currently studying opinions and suggestions raised by some NPC deputies,” the statement said.

Monday’s ruling said the ban infringes on fundamental rights more than is reasonably necessary. The ban has been widely disregarded.