DERNA, Libya -- Libyan authorities demanded an investigation on Thursday into whether human failings were to blame for thousands of deaths in the worst natural disaster in the country's modern history, as survivors searched for loved ones washed away by floods.

A torrent unleashed by a powerful storm burst dams on Sunday night and hurtled down a seasonal riverbed that bisects the eastern city of Derna, washing multi-storey buildings into the sea with sleeping families inside.

Confirmed death tolls given by officials have varied. All are in the thousands, with thousands more on lists of the missing. Derna Mayor Abdulmenam al-Ghaithi said deaths in the city could already reach 18,000-20,000, based on the extent of the damage.

He told Reuters he was afraid the city would now be infected with an epidemic, "due to the large number of bodies under the rubble and in the water".

Rescue workers carry a dead body amidst rescue operations in the aftermath of the floods in Derna, Libya September 13, 2023 in this screen grab obtained from a video. AL-Masar TV/Handout via Reuters

The World Meteorological Organization said the huge loss of life could have been avoided if Libya - a failed state for more than a decade - had a functioning weather agency in place.

"If there would have been a normally operating meteorological service, they could have issued warnings," WMO Secretary-General Petteri Taalashe said in Geneva. "The emergency management authorities would have been able to carry out evacuation of the people. And we could have avoided most of the human casualties."

Other commentators drew attention to warnings given in advance, including an academic paper published last year by a hydrologist outlining the city's vulnerability to floods and the urgent need to maintain the dams that protected it.

Mohamed al-Menfi, head of the three-member council that acts as the presidency in Libya's internationally recognised government, said on X that the council had asked the attorney general to investigate the disaster.

Those whose actions or failure to act were responsible for the failure of the dam should be held accountable, along with anyone who held up aid, he said.

General view of the city during the Sunrise, following a powerful storm and heavy rainfall hitting the country, in Derna, Libya September 14, 2023. Photo: Reuters

Usama Al Husadi, a 52-year-old driver, had been searching for his wife and five children since the disaster.

"I went by foot searching for them ... I went to all hospitals and schools but no luck," he told Reuters, weeping with his head in his hands.

Husadi, who had been working the night of the storm, dialled his wife's phone number once again. It was switched off.

"We lost at least 50 members from my father’s family, between missing and dead," he said.

Wali Eddin Mohamed Adam, 24, a Sudanese brick factory worker living on Derna's outskirts, had awakened to the boom of the water on the night of the storm and rushed to the city centre to find it was gone. Nine of his fellow workers were lost, and around 15 others had lost their families, he said.

"All were swept away by the valley into the sea," he said. "May God have mercy upon them and grant them heaven."

International aid

Rescue teams arrived from Egypt, Tunisia, the United Arab Emirates, Turkey and Qatar. Among countries sending aid, Turkey sent a ship carrying equipment to set up two field hospitals. Italy sent three planes of supplies and personnel, as well as two navy ships that had difficulty offloading because Derna's debris-choked port was almost unusable.

The World Health Organization (WHO) said it would release $2 million from its emergency fund to support the victims, calling the floods a "calamity of epic proportions". It added it would send trauma, surgical and emergency supplies from its logistics hub in Dubai.

Rescue work is hindered by the political fractures in a country of 7 million people, at war on-and-off and with no government holding nationwide reach since a NATO-backed uprising toppled Muammar Gaddafi in 2011.

Graphics: Reuters

An internationally recognised Government of National Unity (GNU) is based in Tripoli, in the west. A parallel administration operates in the east, under control of the Libyan National Army of Khalifa Haftar, who failed to capture Tripoli in a bloody 14-month siege that unravelled in 2020.

Derna has been particularly chaotic, run by a succession of armed Islamist groups, including at one point Islamic State, before being uneasily brought under Haftar's control.

A delegation of GNU ministers were expected in Benghazi in the east on Thursday to show solidarity and discuss relief efforts, a rare occurrence since the eastern-based parliament rejected their administration last year.

Viewed from high points above Derna, the once densely populated city centre was now a wide, flat crescent of earth with stretches of mud. Nothing but rubble and a washed out road were left on Thursday at the site of the dam that had once protected the city. The desert riverbed, or wadi, had already subsided back to a trickle.

Below, the beach was littered with clothes, toys, furniture, shoes and other possessions swept out of homes by the torrent. Streets were covered in deep mud and strewn with uprooted trees and hundreds of wrecked cars, many flipped on their sides or roofs. One car was wedged on a gutted building's second-floor balcony.

"I survived with my wife but I lost my sister," said Mohamed Mohsen Bujmila, a 41-year-old engineer. "My sister lives downtown where most of the destruction happened. We found the bodies of her husband and son and buried them."

He also found the bodies of two strangers in his apartment.

As he spoke an Egyptian search-and-rescue team nearby recovered the body of his neighbour.

"This is Aunt Khadija, may God grant her heaven," Bujmila said.