The Hong Kong Alliance for the Patriotic and Democratic Movement said its vice chairman Zhou Hengdong was arrested by the police on Friday morning. It is not clear why Zhou was arrested, and the police have not yet commented on the matter.

The alliance organized a vigil and held a museum to commemorate the Tiananmen Square incident on June 4. The museum is closed this week.

After the police warned that it might be illegal to celebrate the anniversary at the usual vigil in Victoria Park, Zhou continued her activism, urging people to light candles in private to commemorate the event no matter where they are.

Last year, despite the ban, thousands of people went to Victoria Park to light candles and sing as a memorial. The police later accused more than 20 activists, including Zhou, of participating in unauthorized gatherings.

The other two main members of the Hong Kong Alliance-Li Zhuoren and Stanley Ho-were jailed for participating in unauthorized gatherings during the large-scale anti-government protests in Hong Kong in 2019.

Zhou said in an earlier interview with the Associated Press that she is expected to be imprisoned for her activism.

“I have been persecuted for participating in and inciting the candlelight vigil last year,” she said.

“If I continue to promote democratic activism in Hong Kong and China, they will definitely catch up with me at some point, so this is to be expected.”