Police in the US state of Utah are investigating the death of a man who crawled into the engine of a Delta Air Lines jet on the ground at Salt Lake City International Airport late Monday, CNN reported.

The airport says the 30-year-old man got onto the secure ramp area of the airport through a terminal emergency exit, “ran to the south end of the airport’s west runway where deicing operations were underway and crawled into an aircraft engine that was not running.”

Emergency responders found the man “unconscious and were not able to revive him,” the airport said. “It is unclear at this time what injuries caused the man’s death.”

The man has been identified as Kyler Efinger, a resident of Park City, Utah, according to the Salt Lake City Police Department.

Efinger had a boarding pass for a flight to Denver, the department said.

Delta Air Lines says Flight 2348—an Airbus A220 about to depart for San Francisco—then returned to the gate, where all 95 passengers deplaned. The flight was ultimately canceled.