A secure messaging app used by protesters to organize in Hong Kong was hit with a massive cyberattack, identifiable from offending IP addresses as coming from mainland China.

Protesters in Hong Kong took to the streets in droves in June to decry legislation that would have allowed Hong Kong citizens wanted by the Chinese government to be extradited for trial to the mainland. Using an app called Telegram, which prides itself on its security, protesters were able to coordinate one of the largest demonstrations the city has seen for years.