A row of houses are left flattened by a tornado in this aerial photograph taken over Granbury, Texas on May 16, 2013. Six people were dead and seven missing after a powerful tornado ripped through a neighborhood that included housing for the poor in the north Texas town of Granbury, marking the deadliest severe storm outbreak in the United States so far this year. REUTERS/Brandon Wade (UNITED STATES - Tags: ENVIRONMENT DISASTER TPX IMAGES OF THE DAY)