A 13-year-old Fort Worth boy is one of two people killed in a big pile-up in Gainesville on Sunday afternoon. Traffic was backed up and going slow through a construction zone on I-35 when an 18-wheeler slammed into the back of a Ford Explorer. The chain-reaction accident included nine vehicles. Fort Worth resident Gervious Hinkle and his grandson Casey were killed and another person in their SUV is now in critical condition at a Dallas hospital. Six others were hurt but not as seriously. Investigators don't know why the truck driver didn't stop.