Police spokeswoman Cpl. Tracey Knight didn't specify how the man died, and said he was believed to be in his late 30s or early 40s. She said alcohol may have been a factor in the incident, which occurred late in the Sprint Cup race.
Knight did not identify the man and wasn't sure of the man's relationship with others involved in the altercation. Several people witnessed the incident, but nobody was in danger, Knight said.
The death occurred "in or around a pickup truck" in part of the infield near the middle of the backstretch, track spokesman Mike Zizzo said.
Police blocked off the area around the incident, and investigators could be seen looking into a truck.