Damascus Police Chief Bill Nunley didn't release the driver's name or age but said he was participating in the parade and he had traversed the Appalachian Trail in the past.
"One of the things that is unique about this filter is even if you didn't have arsenic in the water and you only had iron, this is still a great filter to filter iron, " said David Nunley.
Mr. Nunley said the man's 1997 Cadillac was one of the last vehicles in the parade and the driver might have suffered an unspecified medical problem when his car accelerated to about 25 miles an hour and struck the crowd on a two-lane bridge along the town's main road.