SIERRA VISTA -- Four people believe they were shot at from south of the border on Tuesday, according to the U.S. Border Patrol. But no evidence has yet been found to substantiate the incident, Border Patrol spokesman Gustavo Soto said Wednesday. U.S. Forest Service investigators also have not found evidence to support the report. "They perceived shots having been fired," Border Patrol spokeswoman Andrea Zortman said Thursday. "We turned everything over to the Park Service." Kym Hall, Coronado National Memorial's superintendent, said four people were stopped as they passed eastbound through the memorial at about 7:45 a.m. for driving erratically....