Four people have been killed and two injured -- including a child -- in separate shootings in Thailand's restive south, local police said Monday.They said two men on motorbikes shot dead a 59-year-old pork vendor early Sunday afternoon, while he was riding home with his nine-year-old nephew in Narathiwat province. The child was injured when he fell from the bike. That evening, a 51-year-old construction worker was also killed and his colleague injured in another drive-by shooting nearby. A Muslim defence volunteer was shot dead in the same province later Sunday night while he was parking his motorbike in front of his house. In neighbouring Yala province that night, a group of armed