Tristan Mericle, 7, killed when he is hit by tractor trailer while riding his bike on Highway 97 in Chester, South Carolina

An 18-wheeler hit and killed a little boy as he rode a dirt bike his parents gave him for Christmas. Seven-year-old Tristan Mericle died after a tractor-trailer struck him Tuesday evening. Troopers and say the seven-year-old was riding a dirt bike in his front yard and drove onto Highway 97, right into the path of the big rig, as he tried to turn the bike around.