The wall of water several feet high smashed into apartment buildings, drowning entire families in minutes.

One man, Fadellalah, believes 13 members of his extended family died. He is yet to hear about the fate of another 20, several days after two dams burst above the Libyan coastal city of Derna, unleashing epic floods that wiped out neighbourhoods and sent some of the dead into the sea.

As a powerful storm bore down on his hometown, Fadellalah, an information technology worker in Libya’s capital Tripoli, called his family on Sunday to urge them to move to higher ground.

“No one expected this,” said Fadelallah, who asked that his surname not be used because he fears reprisal from government officials and armed groups who could view his story as criticism of their efforts.

“Some of them didn’t have cars. They didn’t have a way to get out.”

Torrential rainwater that gushed down steep mountainsides and into the city killed thousands. Those who survived recount nightmarish scenes, with bodies piling up more quickly than authorities could count.

Mediterranean Storm Daniel caused deadly flooding in many towns of eastern Libya. But Derna, renowned for its white villas and palm trees, was the worst hit. The city had no evacuation plans, and residents said the only warning was the explosive sound of the dams rupturing.