Rescue teams in Libya are struggling to recover the bodies of victims who were swept out to sea in tsunami-like floodwaters.
At least 2,300 were killed, according to the ambulance authority in Derna, the worst-hit city.
Two dams and four bridges collapsed in Derna, submerging much of the city when Storm Daniel hit on Sunday.
Around 10,000 people are missing, the Red Crescent says, and the death toll is expected to rise further.
Some help has started to arrive, including from Egypt, but rescue efforts have been hampered by the political situation in Libya, with the country divided between two rival governments.
The United States, Germany, Iran, Italy, Qatar and Turkey are among the countries that have said they have sent or are ready to send aid.
Video footage recorded after sunset on Sunday shows a river of flood water flowing through the city with cars floating helplessly in the current.
There are heartbreaking stories of people being swept out to sea, while others clung to roofs to survive.
“I was shocked by what I saw, it’s like a tsunami,” said Hisham Chkiouat, of the eastern Libyan government.
He told BBC Newshour that the collapse of one of the dams south of Derna had swept much of the city into the sea.
“A huge neighborhood has been destroyed: the number of victims is high and increases by the hour.”
Al-Dbeibah said rescue teams were struggling to recover some bodies and that the navy and divers were trying to recover bodies from the sea.
Kasim Al-Qatani, an aid worker in the town of Bayda, told the BBC’s Newsnight program that it was difficult for rescuers to reach Derna as most of the main roads into the town were “out of order due to the enormous damage”.
An investigation had been launched into why the floods were able to cause such devastation, he said, adding that 2.5 billion Libyan dinars (£412 million; $515 million) would be donated to help rebuild Derna and the eastern city of Benghazi.
The cities of Soussa, Al-Marj and Misrata were also affected by Sunday’s storm.
Water engineering experts told the BBC that it is likely that the upper dam, about 12 km (eight miles) from the city, failed first, sending water down the river valley towards the second dam, which is located further away. near Derna, where neighborhoods were flooded. .
“At first we just thought it was heavy rain, but at midnight we heard a loud explosion and it was the dam collapsing,” Raja Sassi, who survived along with his wife and young daughter, told the Reuters news agency.
Libyan journalist Noura Eljerbi, who lives in Tunisia, told the BBC she only discovered that around 35 of her relatives, all living in the same apartment block in Derna, were still alive after contacting a local rescue team.
“The house was destroyed but my family managed to get out before things got worse. They are safe now,” he said.
Rescue worker Kasim Al-Qatani told BBC Newsnight that in Derna there is no clean drinking water and a lack of medical supplies.
He added that Derna’s only hospital can no longer accept patients because “there are more than 700 corpses waiting in the hospital and it is not that big.”
Libya has been in political chaos since longtime ruler Col Muammar Gaddafi was overthrown and killed in 2011, leaving the oil-rich nation effectively divided with an internationally recognized interim government operating from the capital, Tripoli, and another to the east.
Libyan journalist Abdulkader Assad said confusion over the matter was hampering rescue efforts.
“There are people promising help but the help isn’t coming,” he told the BBC. “There are no rescue teams, there are no trained rescuers in Libya. For the last 12 years everything was about the war.”
But despite the split, the Tripoli government sent a plane with 14 tons of medical supplies, body bags and more than 80 doctors and paramedics.
Brian Lander, deputy director of emergencies at the United Nations World Food Programme, said the organization has food supplies for 5,000 families.
Derna, about 250 km east of Benghazi along the coast, is surrounded by the nearby hills of the fertile Jabal Akhdar region.
The city was once where Islamic State militants built a presence in Libya after the fall of Gaddafi. They were expelled a few years later by the Libyan National Army (LNA), forces loyal to General Khalifa Haftar, an ally of the eastern administration.
The powerful general said eastern officials were currently assessing flood damage so roads could be rebuilt and electricity restored to aid relief efforts.
Libya’s leading news site Al-Wasat has suggested that the failure to adequately rebuild and maintain infrastructure in Derna after years of conflict is partly responsible for the high death toll.
“The chaos in terms of security and the laxity of the Libyan authorities in carrying out careful monitoring of security measures [of the dams] it led to catastrophe,” said economic expert Mohammed Ahmed.
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