Hong Kong police on Wednesday morning arrested about 53 former lawmakers and pro-democracy activists in an unprecedented crackdown under the national security law. Majority of those targeted had participated in unofficial election primaries for the territory’s legislature in July, which drew more than 600,000 voters. The national security law carries a maximum life sentence for subversion, secession, terrorism, and collusion with foreign powers.

Who are those targeted? They include at least seven members of Hong Kong’s Democratic Party, the largest opposition party. Former lawmaker Lam Cheuk-ting recorded the moment police showed up at his house, saying he was “suspected of violating the national security law, subverting state power.” Police arrested Benny Tai, a leader in the 2014 Occupy Central protests and one of the major organizers of the primaries. They also raided the home of Joshua Wong, an activist currently serving 13½ months in prison for organizing and participating in an unauthorized protest last year.

Dig deeper: Read Erica Kwong’s report on Hong Kong’s financial crackdown on a church that supports protesters.