Police said Democratic Party lawmakers Lam Cheuk-ting and Ted Hui were among 16 people arrested. Both lawmakers had their own arrests filmed at their homes.
Lam was arrested on suspicion of rioting on July 21, 2019, when a mob of over 100 men wielding sticks and poles attacked pro-democracy protesters, journalists and bystanders at a train station in the Yuen Long district, near the mainland border.
During the 2019 incident, Lam was hospitalised after being wounded in the face as he live-streamed the attack on his Facebook page.
Senior police superintendent Chan Tin-chu told a news conference that the police thought the attacks came from both the white-shirted mob and black-clad protesters, and Lam's presence aggravated the situation.
During his arrest on Wednesday (August 26), Lam Cheuk-ting was filmed saying: "Hong Kong police have now regressed to being a political tool. What happened on July 21 (last year) was outrageous and you framed a victim as an attacker, don't you feel ashamed of this (law) enforcement operation?"