Hong Kong’s pro-democracy lawmakers resigned en masse after four of them were ousted from the semiautonomous Chinese territory’s Legislature in a move one legislator said could sound the “death knell” for democracy there.

The resignation of the 15 remaining pro-democracy lawmakers will ratchet up tensions over the future of Hong Kong, a former British colony that has long been a regional financial hub and bastion of Western-style civil liberties but over which China’s government has increasingly tightened its control. A new national security law imposed by Beijing this year has alarmed the international community. For more, watch the full video.