An investigation is ongoing following the discovery of a body in a wheel compartment of a United Airlines flight that took off from Chicago and landed in Hawaii Tuesday. Flight 202 left O’Hare Christmas Eve.

Police say a body was found in one of the main landing gears of a United Airlines plane that arrived in Maui after taking off from Chicago Tuesday. United says the wheel well is only accessible from the outside.

The wheel well was only accessible from outside the plane, and it wasn’t clear Wednesday how or when the person accessed the space, according to United Airlines.