A man flying on a United Airlines flight from Denver to Salt Lake City died Sunday, multiple websites report, but when and how the man died remains unclear.

The man was unidentified, but was said to be in his 30s. Reports of when the man died or whether he died on the plane or shortly after disembarking are conflicting. 

United Airlines spokeswoman Megan McCarthy says the man collapsed on the jetway leading to the terminal, the Associated Press reports.

However a report by the website TravelersToday stated that the man died while still on the plane and that passengers on the plane spent about 30 minutes trying to revive him.

One of the passengers who attempted CPR was Jared Noall, a trained combat medic, reported KSL, a Utah-based news outlet.

Noall, a resident of Ogden, Utah, not far from where flight 5596 landed in Salt Lake City, said he heard the man snoring loudly from a few rows behind him for 15 to 20 minutes before the plane landed, but after the man stopped snoring Noall assumed he had found a comfortable sleeping position, KSL reported.

After the plane landed it became clear to passengers that something was wrong with the man. Noall said when he turned around to look at the man he immediately thought the man was dead, KSL reported.

"You could tell something was wrong. I asked, 'Hey, sir, are you awake?'" Noall said to KSL. "I shook him a bit, trying to see if I could get a response out of him. We checked his throat for a pulse, and it wasn't there, so we laid him down in the aisle and start CPR."

Using a defibrillator, Noall and two others preformed CPR on the man until paramedics arrived and the man was taken off the plane. The man was pronounced dead after half an hour, reported KSL.

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