On Monday, small towns in Oklahoma began a long cleanup after tornadoes flattened homes and buildings and killed four people, including an infant, widening a destructive outbreak of severe weather across the middle of the United States. According to state officials, punishing storms that started late Saturday in Oklahoma damaged a rural hospital, flooded roads, and at one point cut off electricity to over 40,000 customers. In Sulphur, a town of about 5,000 people south of Oklahoma City, a tornado caused extensive damage, tearing off the roofs of houses, automobiles, and buses within a 15-block…