TikTok went offline in the United States Saturday night, less than two hours before a ban was slated to go into effect. The extraordinary blackout prevents access to one of the world’s most popular social media apps – one that had been used by 170 million Americans.

Visitors to the app were met with a message reading: “Sorry, TikTok isn’t available right now. A law banning TikTok has been enacted in the U.S. Unfortunately, that means you can’t use TikTok for now.”