A Crossville man was killed Saturday in Warren County when he crashed after jumping his four-wheeler over a hill while riding in the Rock Island area with a friend.The man, Timothy A. Hicks, 33, died at the scene of the Saturday morning accident.According to Sheriff Jackie Matheny, the fatal crash happened around 9 a.m. at a location off Webb Lane in the Rock Island community. “Mr. Hicks was riding a four-wheeler and the men approached a jump,” Matheny said of the accident. “At that point, Hicks took the jump and his friend decided not to try it and instead drove around the jump.”The area where the accident happened is an unofficial off-road track which has been somewhat carved out of a wooded area and has been used by other four-wheeler riders and motorcycle enthusiasts in the past.“When his friend got around the jump, he found Mr. Hicks face down at the bottom of the jump, his four-wheeler stopped a ways on down in a brier thicket,” Matheny said, noting the victim died by the time help arrived.An investigation reveals it appeared Hicks’ four-wheeler had rotated forward while in the air and had rolled end over end when it struck the ground, throwing the victim off.Matheny noted Hicks was not wearing a helmet.