Passengers have been evacuated from a plane at an international airport in the US after flight attendants uncovered a written threat.

According to a statement from Southwest Airlines, the crew working on flight 2104 from Pheonix identified a written threat upon arrival into Baltimore/Washington International Thurgood Marshall (BWI) Airport on 11 January.

“Our crew followed protocol by notifying the appropriate authorities and moving the aircraft to a remote location while awaiting further instruction,” the airline said.

“The authorities promptly arrived and boarded the aircraft, safely transferring the 95 passengers and six crew members to the airport terminal via buses.

“We are fully cooperating with authorities as they take extra precautionary measures and thoroughly review of the aircraft. We apologise to our customers for the inconvenience – the safety of our employees and customers always remains our utmost priority.”

Precisely what the written threat contained has not yet been made public.

BWI airport posted a statement to Twitter confirming the incident, and said law enforcement investigated a “suspicious message” that was discovered on board the flight.

“Out of an abundance of caution, the aircraft was parked at a remote area of the airfield,” the statement read.

“Passengers were offloaded safely from the aircraft on to shuttle buses and brought to the airport terminal.

“Law enforcement personnel concluded their investigation and determined there was no credible threat.”

Fox Business reported that the FBI is now investigating law enforcement at BWI airport.

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