Federal authorities are at Philadelphia International Airport because of an apparent bomb threat that was made in connection with an incoming flight from Ireland.
The plane is USAirways Flight 777 from Shannon Airport to Philadelphia.
FBI spokeswoman Carrie Adamowski says Wednesday that agents are assisting Transportation Security Administration officials in the investigation.
Emergency officials met the plane when it landed and passengers were exiting the plane to waiting buses to be driven to the terminal.
Police and airport officials say they don't have any specifics about the apparent threat or details about from where it may have originated.
U.S. customs and border protection have screening facilities at Shannon Airport and the passengers aboard the plane would have gone through them before boarding.
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