United Airlines said a dead body was discovered in the wheel well of one of its planes after it landed in Maui from Chicago on Christmas Eve.

At this time, it is not clear how or when the person accessed the wheel well,” the airline said, noting it is working with law enforcement on the incident.

Customers on a Delta Air Lines flight from Seattle to Honolulu were delayed by several hours after someone snuck on board. The Atlanta-based airline released a statement to ABC News on Thursday afternoon that confirmed an “unticketed passenger” made their way onto the Christmas Eve flight and had to be removed from the plane.