Story highlights The incident was reported to the Transportation Security Administration two days later

Sources within the Federal Air Marshal Service said the agent in question is a relatively new hire

(CNN) A federal air marshal on a transatlantic flight left her loaded service weapon in the airplane's bathroom, where it was discovered by a passenger who gave it to a crew member before it was returned to the federal agent, CNN has learned.

The incident happened aboard Delta flight 221, which was traveling from Manchester, United Kingdom, to New York's John F. Kennedy International Airport on April 6, and was reported to the air marshal's management days later.

In a statement to CNN the TSA would confirm only that it is aware of an incident involving a federal air marshal on that date, and it is reviewing the circumstances.

A Delta spokesperson said the airline is also aware of the incident but declined to provide further comment.

Sources within the Federal Air Marshal Service said the agent in question is a relatively new hire who should have been placed on leave for leaving her gun. Instead, the agent remains on active flight duty, CNN has been told.

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