The Herald of Rock Hill reported the holdup occurred late Saturday night at the "Trail of Terror" near state Highway 901 and Interstate 77.
Volunteer Kristy Sims says people ran when the robber opened fire near the entrance.
The ticket collector, 56-year-old James Douglas Rockholt, was being treated at Carolinas Medical Center in Charlotte, N.C., for a gunshot wound to the arm. No other injuries were reported.
No arrests have been made.
Volunteers say they plan to keep the trail open to raise money for the Children's Miracle Network. Some money will also go for Rockholt's medical costs.
More security guards are being added.