A large number of pro-democracy student leaders from Hong Kong, protesting against Beijing's decision to vet candidates in 2017 elections, have been denied entry into China.
According to the Washington Post, the action has alarmed various people and has sparked belief that the Chinese authorities are arranging a blacklist with hundreds or thousands of names.
Last week, three leaders of the protest were stopped while trying to fly to Beijing to hold talks with Chinese leaders.
Eric Tang, 21, a student at the Open University of Hong Kong, said he was turned away on November 9 while he was trying to go to Shenzhen with his girlfriend to shop.
For some people, the denials threaten their livelihood due to how Hong Kong's economy is with mainland China's.