A global humanitarian aid effort for disaster-hit Libya picked up pace Thursday after a tsunami-sized flash flood ripped through a coastal city, killing over 5,100 people, with thousands more missing and feared dead.

The enormous surge of water burst two upstream river dams and reduced the city of Derna to an apocalyptic wasteland where entire city blocks and untold numbers of people were washed into the Mediterranean Sea.

Hundreds of body bags now line its mud-caked streets, awaiting mass burials, as traumatized and grieving residents search mangled buildings for missing loved ones and bulldozers clear streets of debris and mountains of sand.

The U.N., United States, European Union and multiple Middle Eastern and North African nations have pledged to send rescue teams and aid including food, water tanks, emergency shelters, medical supplies and more body bags.

The floods were caused by hurricane-strength Storm Daniel, compounded by poor infrastructure in Libya, which descended into years of war and chaos after a NATO-backed uprising in 2011 toppled and killed longtime dictator Moammar Gadhafi.

Libya is now divided between two rival blocs – the U.N.-backed, internationally recognized government in Tripoli, and an administration based in the disaster-hit east.

Access to Derna in the east remains severely hampered as roads and bridges have been destroyed and power and phone lines cut to wide areas, where at least 30,000 people are now homeless.

The catastrophe's true death toll remained unknown, and officials have provided conflicting numbers.

A total of 3,840 bodies had been recovered by Wednesday, said Lieutenant Tarek al-Kharraz, spokesman for the Interior Ministry of the administration ruling eastern Libya.

But many more people may have been washed out to sea or buried in the sand by the wall of muddy water that tore through the city late Sunday, peaking as high as the second story of buildings.

The International Federation of Red Cross and Red Crescent Societies has warned that 10,000 people are missing.

One man in the city recounted how the rains lashed the area from early evening, before the massive flood surge hit after midnight: "At around 2 a.m. I was at home on the third floor when the floodwaters began to wash away the cars in the street."

'Overcome divisions'

Aid has been sent or promised by numerous regional nations including Algeria, Egypt, Jordan, Kuwait, Qatar, Tunisia, Türkiye and the United Arab Emirates (UAE) as well as the Palestinians.

Among the first aircraft to arrive in Benghazi, a 300-kilometer (180 mile) drive from Derna, have been eight Emirati planes carrying rescue teams, hundreds of tonnes of relief goods and medical aid.

The United States has also pledged to help, and in Europe the aid effort has been joined by Britain, Finland, France, Germany, Italy and Romania.

Climate experts have linked the disaster to the impacts of a heating planet combined with Libya's years of chaos and decaying infrastructure.

Storm Daniel gathered strength during an unusually hot summer and earlier lashed Türkiye, Bulgaria and Greece.

"Storm Daniel is yet another lethal reminder of the catastrophic impact that a changing climate can have on our world," said U.N. High Commissioner for Human Rights Volker Türk.

Türk called on all sides in Libya "to overcome political deadlocks and divisions and to act collectively in ensuring access to relief.

"This is a time for unity of purpose: all those affected must receive support, without regard for any affiliations."

Landmine threat

In the aid effort since the floods hit, the Tripoli-based government has declared a national emergency and deployed aircraft, rescue crews and trucks filled with aid.

The United Nations has pledged $10 million in support.

The need is huge, with at least 30,000 people made homeless in Derna and eastern areas, where other towns and villages were also hit by floods and mudslides, according to U.N. agencies.

"Obstructed, destroyed and flooded roads severely undermine access to humanitarian actors," the International Organization for Migration said.

"The bridges over river Derna that connect the eastern part of the city to the west have collapsed."

In an additional threat, landmines left over from the war may have been shifted by the floods, warned Erik Tollefsen, head of the weapon contamination unit at the International Committee of the Red Cross.