Hong Kong police on Wednesday morning arrested four leaders of a pro-democracy group, alleging the group was working as a “foreign agent.” The Hong Kong Alliance in Support of Patriotic Democratic Movements of China is known for organizing the city’s annual vigil commemorating those who died in Beijing’s Tiananmen Square massacre in 1989. The arrested members of the group included vice chairwoman and barrister Chow Hang-tung, as well as standing committee members Leung Kam-wai, Tang Ngok-kwan, and Chan Dor-wai. The Hong Kong police sent a letter to the group last month, citing the national security law introduced by Beijing last year. The police alleged the group to be a “foreign agent” and requested it hand over its membership and financial information no later than Sept. 7. In response, the group went to the Wan Chai Police Headquarters, stated the request was based on “reasonable grounds to believe,” which has no …