The incident occurred in a parking lot at the stadium while the Chiefs played the Denver Broncos just inside the venue, Kansas City, Missouri, police spokesman Tye Grant said.
The altercation began when someone left the game and found the man -- who later died at an area hospital -- inside their car. The man may have owned a similar car, Grant said.
"The incident did not involve any fan rivalry," Police Chief Darryl Forte said in a Twitter post.
No one is in police custody, Grant said.