CNN said Wednesday a derogatory tweet about President Trump sent from host Anderson Cooper’s account did not come from Cooper, but rather an unknown individual who gained access to the account through a cellphone belonging to his assistant.

The network said in a statement it confirmed using geolocation tools the tweet, which called Trump a “pathetic loser” and a “tool,” was sent from New York. Cooper was in Washington, D.C., at the time.

The tweet was sent from a phone that belongs to Cooper’s longtime assistant, CNN said.

The assistant left the phone “unlocked and unattended” while at the gym on Wednesday morning, and CNN said an unknown person took the phone and posted the tweet.

Only Cooper and the assistant, who has worked with the host for more than 10 years, have access to Cooper’s Twitter account.

The tweet in question was a response to Trump’s tweet Wednesday morning about the Alabama Senate special election.

“The reason I originally endorsed Luther Strange (and his numbers went up mightily), is that I said Roy Moore will not be able to win the General Election. I was right! Roy worked hard but the deck was stacked against him!” Trump tweeted.

Cooper’s account replied, “Oh Really? You endorsed him you tool! Pathetic loser.”

Cooper attributed the errant tweet to a hacker.

“[J]ust woke up to find out someone gained access to my twitter account,” he tweeted. “I have not sent a tweet in days or replied to any tweets. We are looking into how this happened.”