The FBI is investigating a bomb threat made in a tweet that prompted the U.S. military to send F-16 fighter aircraft to escort two jets bound for Atlanta on Saturday, the Associated Press reports .
The threats involved a Southwest Airlines flight from Milwaukee and a Delta Air Lines flight from Portland, Oregon.
Authorities scoured the planes and found no evidence of bombs.
“We certainly take these types of threats seriously and we’re pursuing them aggressively,”Federal Bureau of Investigation  Special Agent Stephen Emmett told The Associated Press on Sunday.
“We are continuing to pursue leads in the efforts to locate this individual,” he added.
The military dispatched the fighter jets after being alerted about the tweet.