Police blocked the entrances and exits of Ngai Wong Commercial Building, where the museum which commemorated the 1989 Tiananmen crackdown is located. A large number of police officers stood guard outside the building.
The museum is run by the Hong Kong Alliance in Support of Patriotic Democratic Movements of China, which also organized Hong Kong's annual June 4 vigil at Victoria Park.
Four core members of the alliance were arrested early yesterday morning, a day after it refused to cooperate in a police probe into the organization. A member filed a judicial review to challenge the police request for materials, including its meeting and bank records.
The four are vice-chairwoman Chow Hang-tung and standing committee members Leung Kam-wai, Tang Ngok-kwan and Chan To-wai.
It is understood that Leung will be brought to the museum to assist the investigation.
The June 4th museum was set up by the Alliance in 2014. It reopened on May 30 this year, but had to close three days later after the government said it was operating without a license.
The group was called a foreign agent by Secretary for Security Chris Tang Ping-keung, who said the public would be able to know details if the case was taken to court.
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