The city of Derna has buried thousands of people in mass graves, Libyan officials said Thursday, as search teams scoured ruins left by devastating floods and the city’s mayor said that the death toll could triple or more. Daniel, an unusually strong Mediterranean storm, caused deadly flooding in towns across eastern Libya, but the worst-hit was Derna. The dams that collapsed outside Derna were built in the 1970s and have not been maintained for years, local media reported. He said most of the dead were buried in mass graves outside Derna, while others were transferred to nearby towns and cities. The dead in eastern Libya included at least 84 Egyptians, who were transferred to their home country on Wednesday.