Two passenger planes were safely escorted by fighter jets to Atlanta’s Hartsfield-Jackson International airport Saturday afternoon, following bomb threats posted online.

Delta flight 1156 – coming from Portland, Ore. – and Southwest flight 2492 – flying from Milwaukee, Wis. – were both bound for Atlanta, when bomb threats were posted on social media. In response, jets were dispatched by the North American Aerospace Defense Command.

Asked whether the threats were credible, F.B.I. spokesman Stephen Emmett said: “That’s the best way to characterize the threats,” the New York Times reported.

No additional information about the threats has been given, but according to local media reports, they originated from Twitter handle @kingzortic, and were sent to the two airlines’ Twitter accounts.

After passengers safely left the planes, their luggage was searched by bomb-sniffing dogs, airport spokesman Reese McCranie told Reuters.

The Times also reported that the airport was partially shut down as a result of the online threats.

In a statement to the Associated Press, Southwest officials said: “Our top priority is the safety of our customers and employees. We cannot comment on the nature of the security situation.”