Greenville (South Carolina) Online reports a couple of recent attacks by a fox. The article doesn't say what kind of fox.
Foxes are too small to prey on people. Their attacks are often a sign of rabies. Children are the most common victims, but rabid foxes also go after adults.
Further information from my books:
The Red Hourglass, Chapter 6: Canid.
Deadly Kingdom, Chapter 16: The Canids and Appendix: Animal-Borne Diseases.