Twitter has completely disabled the ability for some accounts to send new tweets following a massive hack on the social media website, which has seen numerous popular accounts — including Barack Obama, Bill Gates, Elon Musk, Joe Biden, and others — tweet out a bitcoin scam.

While Twitter hasn’t confirmed how the block works, it appears to only apply to accounts that have been verified by Twitter. Unverified accounts seem to still be able to tweet normally, and verified accounts appear to be able to retweet existing tweets. It’s unclear how broadly Twitter has disabled the ability to send new tweets or how long it will be before verified users are able to tweet again.

A 6:18PM ET tweet from Twitter confirming that some users may be unable to tweet also notes that password resets may be disabled while Twitter works to correct the situation. Twitter said an hour later that it was continuing to limit tweets, password resets, and “and some other account functionalities.” Some Verge staffers have also been logged out of their accounts since Twitter began limiting tweeting.

Twitter’s verification system grants a blue checkmark to let users know that an “account of public interest is authentic.” Verification status is used by the company to signify that accounts belonging to brands, politicians, and other public figures are real. The verification process has been subject to plenty of controversy over the years, and Twitter has put the verification request system on hold since 2017 (with exceptions made for political candidates for the 2020 election cycle and public health officials in the wake of the COVID-19 pandemic).

Update July 15th, 7:42PM ET: Added additional context from Twitter support and that Verge staffers have been logged out of Twitter accounts.