The National Park Service said 56-year-old Keith Sidwell shot and killed another man on the Blue Ridge Parkway near Roanoke's Explore Park around 10:30 a.m.
Details surrounding the incident are limited; however, chief ranger Neal Labrie said one person "presented a weapon and the other responded with shooting."
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Officials said Sidwell called police to report the shooting right after it happened.
The unidentified victim was transported to Roanoke Memorial Hospital where he later died.
Sidwell was arrested, but no charges have been listed, WSET reports.
The FBI and the U.S. Attorney's office are involved in the investigation.
Sidwell retired from the Henderson Police Department in May of 2013.