A passenger boarded a Delta Air Lines (DAL.N), opens new tab flight from New York to Paris without a ticket, somehow evading two boarding pass checks and leading both Delta and the U.S. Transportation Security Administration to say they were investigating how it happened.

French police boarded the plane in Paris and took the stowaway into custody on Wednesday before the other passengers were let off the plane, CNN reported, citing a ticketed passenger who was onboard.

Delta Flight 264 left New York's JFK Airport on Tuesday night and landed at Paris' Charles de Gaulle Airport on Wednesday.