U.S. President Donald Trump’s @realdonaldtrump Twitter twtr account was “inadvertently deactivated” due to human error by a Twitter Inc employee on Thursday and was down for 11 minutes before it was restored, the social media company said.

“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.

A Twitter representative declined to comment further.

The White House did not immediately respond to a request for comment.

For more on Donald Trump’s Twitter account, watch Fortune’s video:

Trump has made extensive use of messages on Twitter to attack his opponents and promote his policies both during the 2016 presidential campaign and since taking office in January. He has 41.7 million followers on Twitter.

“Great Tax Cut rollout today. The lobbyists are storming Capital Hill, but the Republicans will hold strong and do what is right for America!” he wrote in his first tweet after Thursday’s outage.

In a similar incident last November, Twitter Chief Executive Jack Dorsey’s account was briefly suspended as a result of what he said was an internal mistake.