HONG KONG (AP) — Four leaders of the group that organized annual Tiananmen Square commemorations in Hong Kong were arrested Wednesday after refusing to cooperate in a national security investigation, the group said.

The Hong Kong Alliance in Support of Patriotic Democratic Movements of China had openly challenged the enforcement of a 14-month-old national security law, saying the police are arbitrarily labeling pro-democracy organizations as foreign agents.

The alliance organized candlelight vigils in Hong Kong on the anniversary of China’s bloody crackdown on protesters in Beijing’s Tiananmen Square in 1989. The event was attended annually by massive crowds, but authorities have banned the vigils for the past two years, saying they violate coronavirus restrictions.

Leaders delivered a letter to police Tuesday rejecting a request for details of the group’s operations and finances. Police earlier warned that failure to comply could result in a fine of 100,000 Hong Kong dollars ($12,900) and up to six months in jail.

There was no immediate announcement from police on the arrests, and police did not respond to a request for comment.

Hong Kong authorities have cracked down on dissent following mass anti-government protests in 2019.

Chow Hang-tung, one of the four arrested, began a series of posts on Facebook shortly before 7 a.m., beginning with two Facebook livestreams during which she says that some people have been ringing the doorbell. Chow, a lawyer, appears to be in her office, and muffled shouting could be heard in the background.

“The worst thing about being arrested is that I’ve not changed into a new set of clothes or brushed my teeth, will my breath overwhelm the national security police?” she wrote in one post.

She had been scheduled to represent pro-democracy activist Gwyneth Ho in court for a bail hearing, and wrote that it's regrettable she won't be able to attend. She also posted a photo of the waterfront view outside her office, saying she’s taking a look at it for the last time.

She also asked on Facebook if anyone had any parting words for her. In less than three hours, supporters left more than 500 comments telling her to take care and thanking her for her work at the alliance.

The group said Tuesday that the police do not have a right to request information from the group because it is not a foreign agent and that authorities did not provide sufficient justification in their request.

“This association believes that the issuance of the letter has no legal basis, so we will not provide any information requested in the letter,” the committee said.

Police are investigating the alliance for allegedly working for foreign interests.

Hong Kong leader Carrie Lam said Tuesday that law enforcement agents may request information from suspected foreign agents or foreign political organizations in accordance with the law.

“If someone openly says that they will flout the law, they can’t call themselves a civic society group,” Lam said.

Dozens of pro-democracy activists have been arrested in the crackdown, and the city has amended electoral laws to increase the number of seats for pro-Beijing legislators while reducing those that are directly elected.

Critics say the national security law, which has been used to arrest over 100 people, rolls back freedoms promised to the former British colony when it was handed over to mainland China in 1997. Hong Kong was promised freedoms not found on the mainland for 50 years, such as freedom of speech and assembly.