Aid teams in Libya are struggling to retrieve bodies of victims swept away by tsunami-like floodwaters.
At least 2,300 have died, according to the Ambulance Authority in Derna, the worst-hit city.
Two dams and four bridges collapsed in Derna, inundating much of the city when Typhoon Daniel hit on Sunday.
The Red Crescent says nearly 10,000 people are reported missing and the death toll is expected to rise.
Some aid has begun to arrive, including from Egypt, but aid operations have been hampered by Libya’s political situation, with the country divided between two rival governments.
The US, 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 dark on Sunday showed a river of floodwater swirling through the city and cars being swept helplessly by the current.
There are heartbreaking stories of people being swept out to sea, while others cling to rooftops to survive.
“I was shocked by what I saw, it’s like a tsunami,” said Hisham Chakiwat, from Libya’s eastern government.
He told the BBC News Hour that large parts of the city had fallen into the sea after a dam collapsed south of Derna.
“A large neighborhood has been destroyed – there is a large number of victims, increasing every hour.”
Qasim al-Qatani, an aid worker in the town of Baida, told the BBC’s Newsnight program that it was difficult for aid workers to reach Derna because most of the main roads into the city were “out of service due to heavy damage”. .
He said an investigation had been launched into why the floods could cause so much damage, adding that 2.5 billion Libyan dinars (£412m; $515m) had been earmarked to help rebuild Derna and the eastern city of Benghazi. will be given.
The cities of Susa, Al Marj and Misrata were also affected by Sunday’s storm.
Water engineering experts told the BBC it was likely that the upper dam, about 12 kilometers (eight miles) from the city, had failed first, sending water down the river valley to another dam. Diya, which is located near Derna – where neighborhoods were flooded. .
Raja Sasi, who survived with his wife and young daughter, told Reuters news agency, “At first we just thought it was heavy rain, but at midnight we heard a loud explosion and the dam collapsed. was exploding.”
Noura al-Jerbi, a Libyan journalist based in Tunis, told the BBC that after contacting the local rescue team, she only found out that around 35 of her relatives, who all lived in the same apartment block in Darna, had just died. are still alive.
“The house has been destroyed but my family managed to get out before the situation worsened. They are safe now,” he said.
Mr. Qatani said that there is no clean drinking water in Darna and there is a shortage of medical supplies.
He added that Darna’s only hospital could no longer take patients because “there are more than 700 dead bodies waiting in the hospital and it is not big enough”.
Libya has been in political chaos since longtime ruler Colonel Muammar Gaddafi was toppled and killed in 2011 – a transitional, international body operating from the oil-rich capital Tripoli. was effectively split with the recognized government and another in the east.
Libyan journalist Abdelkader al-Assad said the confusion surrounding him was hampering rescue efforts.
“You have people promising help but help is not coming,” he told the BBC. “There are no rescue teams in Libya, no trained rescuers. The last 12 Over the years everything was about war.”
But despite the split, the government in Tripoli has sent a plane with 14 tonnes of medical supplies, body bags and more than 80 doctors and medical staff.
Brian Lander, deputy director of emergencies at the United Nations World Food Program, 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, after the fall of Gaddafi, fighters from the Islamic State group established a presence in Libya. He was ousted a few years later by the Libyan National Army (LNA), forces loyal to General Khalifa Haftar and affiliated with the eastern administration.
The powerful general said eastern authorities were currently assessing the damage caused by the floods in order to rebuild roads and restore power to aid rescue efforts.
Al-Wasat, a leading Libyan news website, has suggested that the failure to restore and maintain infrastructure in Derna after years of conflict is partly responsible for the high death toll.
“The security chaos and the laxity of the Libyan authorities to closely monitor [the dams’] safety measures led to the disaster,” he quoted economist Mohamed Ahmed as saying.