The flooding swept away entire families in Derna on Sunday night and exposed vulnerabilities in the oil-rich country that has been mired in conflict since a 2011 uprising that toppled long-ruling dictator Moammar Gadhafi.
In the city of Derna alone, at least 5,200 people died, said Tarek al-Kharraz, a spokesperson for the interior ministry of the government that oversees Eastern Libya.
Satellite photos of the city of Derna, which is at the centre of the devastation, days prior to the devastation showed idyllic blue water lapping along the coast of the densely-populated city.