Authorities have made an arrest in the a hit-and-run that injured an 8-year-old boy as he got off the bus in Henry County yesterday afternoon.  State police say 57-year-old David Paul Walker of Martinsville hit the boy and drove away. The boy was flown to the hospital with life-threatening injuries.  Walker s charged with one felony count of hit-and-run. He is currently being held without bond at the Henry County Jail.