More than 1,000 corpses were collected, including at least 700 that have been buried so far, the health minister for eastern Libya said. Derna’s ambulance authority put the current death toll at 2,300.

Footage showed dozens of bodies covered by blankets in the yard of one hospital. Another image showed a mass grave piled with bodies. More than 1,500 corpses were collected, and half of them had been buried as of Tuesday evening, the health minister for eastern Libya said.

The destruction came to Derna and other parts of eastern Libya on Sunday night. As Storm Daniel pounded the coast, Derna residents said they heard loud explosions and realised that dams outside the city had collapsed.

Flash floods were unleashed down Wadi Derna, a river running from the mountains through the city and into the sea.

Outside help was only just starting to reach Derna on Tuesday, more than 36 hours after the disaster struck. The floods damaged or destroyed many access roads to the coastal city of some 89,000.

The deputy mayor of Derna, Ahmed Madroud, told Al Jazeera that “at least 20 percent of the city has been destroyed.”

He said the reason behind the devastation was related to the weak infrastructure in the city and the fact that many buildings were clustered in narrow streets located close to the river.

“When the river overflowed its banks, it just took all the buildings with it, and the families that were in it,” he said.

‘State of grief’

Videos posted online by residents showed large swaths of mud and wreckage where the raging waters had swept away neighbourhoods on both banks of the river.

Multi-storey apartment buildings that once were well back from the river had facades ripped away and concrete floors collapsed.

On Tuesday, local emergency responders, including troops, government workers, volunteers and residents dug through rubble looking for the dead. They also used inflatable boats to retrieve bodies from the water.

Al Jazeera’s Emaduldin Bileid says hundreds of volunteers from western Libya are heading to the east of the country to provide support, while dozens of civil society groups are collecting aid to deliver it to Derna by land and air.

After more than a decade of turmoil, Libya remains divided between two rival administrations: one in the west and the other in the east, each backed by different militias and foreign governments.

“All of Libya is experiencing a state of general grief,” Bileid said. “As soon as the disaster occurred, all political differences ended, and everyone agrees on the need to intensify to overcome this ordeal.”

Gilles Carbonnier, vice president of the International Committee of the Red Cross, told Al Jazeera the situation in eastern Libya “is extremely dire”.

“Hundreds and hundreds of people may have died, thousands more affected, people missing,” he said.

‘Days to prepare’

According to Anas El Gomati, founder and director of Sadeq Institute, a Tripoli-based public policy think tank, although the presence of two rival governments in Libya has complicated authorities’ efforts to respond to the crisis, they had plenty of time to coordinate a better response.

“We had days and hours ahead of this to be able to prepare,” said El Gomati, referring to the storm’s impact on Turkey and Greece days before reaching Libya.

“Unlike the situation in Morocco, where tectonic plates moved and they had seconds to prepare, in Libya, as the dams began to swell and fill slowly, they had days and hours to plan an evacuation. ”

The storm hit other areas in eastern Libya, including the town of Bayda, where about 50 people were reported dead. The Medical Center of Bayda, the main hospital, was flooded and patients had to be evacuated, according to footage shared by the centre on Facebook.

Other towns that suffered included Susa, Marj and Shahatt, according to the government.