What you need to know:
- The true death toll remains unknown, with the health minister of divided Libya's eastern administration, Othman Abdeljalil, saying 3,283 people were confirmed dead in Derna.
Derna. It was long past midnight when Abdel Moneim Awad al-Sheikh awoke to desperate screams from outside his home in the Libyan city of Derna, only to find his building engulfed by surging flood waters.
"I took nothing but my glasses and phone and fled as the waters shook the iron doors like an earthquake," recounted the 73-year-old survivor of the deadly disaster.
He and his family managed to escape their first-floor home and rush up the stairs of the multi-storey building as the raging waters tore away the front door and swept it into the darkness.
From the top floor, they watched in horror as the tsunami-like tidal wave swept away entire buildings, cars and the people inside them, washing untold numbers into the Mediterranean Sea.
The enormous flood, fuelled by torrential rains on September 10, had broken through two upstream dams and sent a tidal wave crashing down the previously dry river bed, or wadi, that bisects the city of 100,000.
A week on, thick mud cakes the devastated building where al-Sheikh and his wife lived, along with two of their sons and their families, in the city where the official death toll has climbed above 3,000.
Scramble onto roof
By the time they had reached the fourth floor that traumatic night, the water had temporarily begun to subside, but it was not the end of the nightmare, said al-Sheikh.
Roughly 20 minutes later, "my son yelled from upstairs and said another, bigger wave, about 20 metres (66 feet) high, is coming".
"We put up a wooden ladder and climbed up onto the second roof, where we stayed until after dawn."
As the sun rose over Derna, now a vast apocalyptic wasteland of shattered buildings and lives lost, a group of volunteers came to help them, most of them young men.
"One of them had lost his entire family," said al-Sheikh.
Amid the chaos, the true death toll remains unknown, with the health minister of divided Libya's eastern administration, Othman Abdeljalil, saying 3,283 people were confirmed dead in Derna.
Libyan officials and humanitarian organisations have warned that the final toll could be much higher, with thousands still missing.
'Mountain of water'
Many who survived the flood lost everything except their lives, their homes now only shells emptied of their contents.
Mohamed al-Zawi, 25, recalled that "all our furniture and things were moving" as water swirled through their home.
The first wave was only at pavement-level, but the second came "with strength", quickly reaching the second and then third floors of his building.
Zawi recalled seeing "a large mountain of water bringing with it cars, people, belongings... and pouring everything out into the sea".
Seated near what was once his home, the shock remains etched onto Zawi's face.
"We had received warnings a day earlier that strong rains were expected and that we should remain at home, but nothing else," he said.
UN experts have blamed the high death toll both on climatic factors and the legacy of Libya's war that has weakened its critical infrastructure, early warning systems and emergency response.
'I saw death'
Zawi said that when he finally managed to come down from the roof, once the waters subsided, he saw "25 or 30 bodies" along the nearby streets.
He rushed to find shrouds for them, he said, before moving on to help the search for any survivors.
In the same neighbourhood, Mohamed Abdelhafiz, a Lebanese national who has lived in Derna for decades, recounted that "the earth shook" that night, and he initially though a quake had hit.
"I saw death," the 50-year-old said, recalling how he had rushed out to his balcony only to find that the water had already reached it.
Standing at an empty window frame, he pointed outside to the shattered city and said: "This whole area, from my house to the wadi, had three or four buildings."
"Now, there is nothing. The ground is just mud, as though there were never any buildings here."