Hong Kong police raided media outlet Stand News and arrested six people connected to the platform for sedition.
More than 200 police officers were deployed during the operation on Wednesday. Police said in a statement on Wednesday they had arrested three men and three women, aged 34 to 73, and that searches of their homes were under way.
Stand News said one of those arrested was Ronson Chan, its deputy assignment editor who is also the head of the Hong Kong Journalists Association.
The news site posted a video of police arriving at Chan's residence and showing their court warrant.
"The charge was conspiracy to publish seditious publications. This is the court warrant and this is my warrant card. Your phone is obstructing our work," an officer is seen saying.
The arrests come as authorities crack down on dissent in the semi-autonomous Chinese city. Police charged former newspaper publisher Jimmy Lai with sedition on Tuesday. His Apple Daily newspaper shut down after its assets were frozen. He was already facing charges under the national security law.
In June, hundreds of police raided the premises of the pro-democracy newspaper Apple Daily, arresting executives for alleged "collusion with a foreign country".
The newspaper subsequently shut down.
