U.S. President Donald Trump’s @realdonaldtrump Twitter account was deactivated by a Twitter Inc employee who was leaving the company on Thursday and was down for 11 minutes before it was restored, the social media company said.

Trump has 41.7 million followers on Twitter and has made extensive use of it to send messages attacking his opponents and promoting his policies, both during the 2016 presidential campaign and since taking office in January.

“We have learned that this was done by a Twitter customer-support employee who did this on the employee’s last day. We are conducting a full internal review,” Twitter said in a tweet.

“We are continuing to investigate and are taking steps to prevent this from happening again,” the company said in an earlier tweet.

Thursday evening’s incident raises a host of questions about how Twitter secures Trump’s personal account, the official @potus presidential account and other accounts that could potentially influence world events.

It comes at a moment when technology companies, including Twitter, face sharp attack from U.S. lawmakers for failing to stem the spread of Russian propaganda and misinformation on their platforms.

Twitter, in particular, has long faced criticism for not doing enough to police its platform and respond to complaints of abuse.

The temporary deletion of the Trump account sparked a flood of criticism on Twitter itself. Reuters could not determine how many Twitter employees had the authority to delete accounts or tamper with them in other ways, such as by sending counterfeit Tweets.

Twitter declined to provide further details.