The plane from Avianca airline was undergoing maintenance in Bogota, Colombia when the discovery was made on Friday.
The bodies were reportedly of two young men, possibly from the Dominican Republic, according to Reuters.
Both bodies had been frozen and were partially thawed, according to a statement from the attorney general’s office.
One man also had burns.
Neither man had documents on them.
However, one man had currency from the Dominican Republic and a suitcase discovered with the men also had paperwork from the country.
“At its arrival to the El Dorado airport in Bogota, personnel from the airline discovered the bodies of two people who flew irregularly (stowaways) in the undercarriage of the airplane,” Avianca said in a statement.
The airline also expressed sympathies to the families of the two men.
The statement also said that while the airline checks its planes before every flight, airport security is the responsibility of authorities.
“The technical investigation body of the attorney general’s office is carrying out urgent actions to identify the nationality and origin of the bodies aged between 15 and 20, Afro-descendent, which were found inside the airplane,” the attorney general’s office said in a statement.
The discoveries of the currency and paperwork “infer that the men could have been on the plane since January 3,” when it was last in the Dominican Republic, the office said.
The plane last received maintenance on December 27, the office said.
Since then, the aircraft has traveled to Bogota, Guarulhos, near Sao Paulo, Brazil, and Santiago.