A group of former lawmakers were among dozens of pro-democracy activists arrested on Wednesday under the national security law imposed by China, per opposition groups and local media.

Why it matters: Hong Kong had enjoyed a high degree of autonomy, but the passage of the sweeping security law by Chinese lawmakers last June has led to a major crackdown on the pro-democracy movement. It has escalated in recent weeks, with the arrests of activists including media tycoon Jimmy Lai and the imprisonment of other prominent figures like Joshua Wong and Agnes Chow.

Those who participated in the pro-democracy primary were arrested this morning for “subversion” under National Security Law.

Apart from my party member, AU Nok Hin, Tiffany Yuen, Fergus Leung, Alvin Yeung, Ventus Lau & Gary Fan have also been arrested so far, and counting. https://t.co/O47VEZxDoM

— LO Kin-hei 羅健熙 (@lokinhei) January 5, 2021

What's new: Police took some 50 people into custody in the crackdown.

• Former lawmakers Alvin Yeung, Lam Cheuk-ting, Andrew Wan and James To were among those arrested "on allegations of subversion" for holding an informal primary last July for a legislative election that was later postponed, per Bloomberg.
• Police also arrested activist Ventus Lau over the 2020 legislative election primaries organized by pro-democracy groups, Bloomberg notes.

Our thought bubble, per Axios contributor Zach Dorfman, of the Aspen Institute: "Watching what's happening in Hong Kong is difficult to stomach — a semi-independent city-state being crushed and blotted out by a vast despotism. It's a very old story, and it strikes at the core of our common understanding of human freedom."

Go deeper: Hong Kong's worst case scenario is happening

Editor's note: This article has been updated with Dorfman's comment.