Phone threats against airlines caused planes to be searched by authorities in Boston, JFK Airport in New York and at Newark Airport yesterday.

One threat was credible enough to cause an Air France flight to receive a military escort from U.S. figher jets to JFK.

The FBI thinks that one caller may have been responsible for calling in the threats.

The anonymous caller claimed there were weapons on the Air France plane and there was a similar threat related to a Saudi Airlines plane.

An American Airlines plane bound for NY from Birmingham, England was held on the tarmac after there was a threat against it. “Authorities initially told the pilot to land and taxi to a remote area away from the terminal but later radioed that the threat was not credible and cleared the plane to go to the terminal minutes after it landed” according to USA Today. 

Other threats received included two Delta flights. Passengers were “removed” from a United flight arriving at Newark from Madrid. That plane got inspected away from the terminal.

Find out more from USA Today here.