TikTok, as it said it would, shut off the video app for U.S. users at about 10:30 p.m. ET on Saturday night. And right now, it’s unclear how long TikTok will stay down.

“Sorry, TikTok isn’t available right now,” the message in the app reads when users opened it. “A law banning TikTok has been enacted in the U.S. Unfortunately, that means you can’t use TikTok for now. We are fortunate that President Trump has indicated that he will work with us on a solution to reinstate TikTok once he takes office. Please stay tuned!”

The message includes a link to TikTok’s website, which includes the same text and informs users they can still log in to download their data. On Friday, TikTok said it will be “forced to go dark” on Sunday, Jan. 19, unless it receives a “definitive statement” from the outgoing Biden administration that the app’s tech partners won’t be penalized under the divest-or-ban law.

TikTok also disappeared from Apple’s App Store and the Google Play app store for Android on Saturday evening. CapCut, a video-editing app owned by ByteDance, also went dark for U.S. users.

President-elect Donald Trump, in an interview Saturday with NBC News, said he “most likely” would issue a 90-day extension to the Jan. 19 deadline. But it isn’t clear he has the legal authority to do that: The law specifies that to trigger a 90-day extension to the Jan. 19 date, the U.S. president must certify to Congress that “relevant binding legal agreements” are in place for ByteDance to enact a divestment of its TikTok ownership. There are no known such agreements in place.

The issue of TikTok’s shutdown came to a head after the Supreme Court rejected the appeal by TikTok and parent ByteDance to halt a law that bans the app in the U.S. as of Sunday unless China-based ByteDance divests its stake in the app to a party that is not located in a country deemed a “foreign adversary.”

Last year, the TikTok divest-or-ban legislation passed with strong bipartisan support, clearing the House of Representatives by a 360-58 vote and the Senate by 79-18. President Biden signed it into law on April 24.

U.S. lawmakers on both sides of the aisle have argued that TikTok is a national security threat, on the theory that China’s communist regime could demand access to data on U.S. users or force TikTok to promote Chinese propaganda. TikTok has repeatedly claimed the Chinese government has never made such demands (and that TikTok would not comply with them if they were made) and says 60% of ByteDance’s ownership is represented by global investment firms.