Two F-16 fighter jets escorted two passenger planes to Atlanta's airport Saturday after they received bomb threats. 

Southwest Airlines Flight 2491 and Delta Flight 1156 landed safely at Atlanta's Hartsfield -Jackson International Airport, according to CNN. The bomb disposal and canine units  searched the planes after the airport received threats on Twitter that military officials deemed credible. 

The Delta flight was traveling from Portland, Oregon to Atlanta, Georgia. The Southwest flight came from Milawaukee, Wisconsin. The fighter jets came from McEntire Joint National Guard Base in South Carolina. They returned to the base once the passenger planes landed safely in the airport. 

FBI special agent Stephen Emmett in Atlanta said the planes were safely on the ground and every precaution was taken to protect the passengers including the scrambling of the military jets, CBS News reported. 

Delta received the first threat in a series of threats around noon EST on Twitter. 

""I have a bomb on one of your planes, but I forgot which one when I left the airport," the message read. "Can you help me find it?"

The person said he/she smuggled the bomb through the back entrance at the airport and placed the bomb on the back of a plane with the help from a friend in airport security. The person ended the series of threats by tweeting that he/she would attack more planes if anything happened to him or her.