Swathes of the Mediterranean city were obliterated by a torrent of water unleashed by a powerful storm that swept down a usually dry riverbed on Sunday night, bursting dams above the city. Multistorey buildings collapsed with sleeping families inside.

Spokesperson of the interior ministry Lieutenant Tarek al-Kharraz on Wednesday told the AFP news agency that 3,840 deaths had been recorded in the Mediterranean city so far, including 3,190 who have already been buried. Among them were at least 400 foreigners, mostly from Sudan and Egypt.

Meanwhile, Hichem Abu Chkiouat, minister of civil aviation in the administration that runs eastern Libya, told the Reuters news agency more than 5,300 dead had been counted so far, and said the number was likely to increase significantly and might even double.

Derna Mayor Abdulmenam al-Ghaithi told Saudi-owned Al Arabiya television the estimated number of deaths in the city could reach between 18,000 to 20,000 based on the number of districts destroyed by the flood.

Derna resident Mahmud Abdulkarim told journalist Moutaz Ali in Tripoli that he lost his mother and brother, after failing to evacuate in time from their first floor apartment following the collapse of a dam.

“She refused to leave her place … didn’t imagine the situation would be horrible and told him [Abdulkarim] it was just ordinary rains,” Ali reported, from an event organised for Tripoli’s Derwani community.

According to Abdulkarim, when his mother and brother did decide to finally leave their apartment, they were swept away by the floodwaters once they reached the streets to flee.

Mabrooka Elmesmary, a journalist who managed to leave Derna on Tuesday, describes the city as a “disaster on a massive scale”. “There is no water, no electricity, no petrol,” she told Al Jazeera. “The city is flattened.”

Apartment buildings with families inside have been swept away, she said. “There’s a wave of displacement as people are trying to flee Derna but many are stuck because a lot of the roads are blocked or gone,” Elmesmary said, adding that some families have been taking shelter in schools.

Officials have put the number of missing at 10,000. The UN aid agency OCHA said the figure was at least 5,000.

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 onto their roofs. One car was wedged on the second-floor balcony of a gutted building.

The devastation is clear from high points above Derna, where the densely populated city centre, built along a seasonal riverbed, was now a wide, flat crescent of earth with stretches of muddy water gleaming in the sun. Buildings were swept away.

Rescue efforts

Rescue teams have arrived from Egypt, Tunisia, the United Arab Emirates, Turkey and Qatar, said Derna mayor al-Ghaithi.

“We actually need teams specialised in recovering bodies,” he said. “I fear that the city will be infected with an epidemic due to the large number of bodies under the rubble and in the water.”

Al Jazeera’s Charles Stratford, reporting from Benghazi, said a field hospital was part of Qatar’s contribution to this “seemingly growing international aid effort to Libya”.

“This is one of three Qatari military … cargo planes expected to arrive in Benghazi today,” Stratford said.

The aid also includes “medical equipment, medicine, food, tents”, Stratford said. “All the aid here is going to be taken to Derna as quickly as possible.”

Moreover, Al Jazeera’s Malik Traina, reporting from Tripoli, said there has been an outpouring of support from Libyans themselves from across the country.

“We haven’t seen this type of unity for many years here in the country,” Traina said.

Large government convoys with equipment from western Libya have arrived in the east, he said. Volunteer convoys with assistance are also heading towards the east.

“We’re seeing also now volunteers and people giving whatever they can – water, food, medicine, whatever supplies they can.”

Rescue operations are complicated by deep political fractures in the country of seven million people that has lacked a strong central government and been at war on and off since a NATO-backed uprising that toppled Muammar Gaddafi in 2011.

An internationally recognised Government of National Unity (GNU) is based in Tripoli, in the west, while a parallel administration operates in the east, including Derna.

Criticism of local authorities in eastern Libya, including those in Derna, has emerged with some saying that locals were not informed that they had to evacuate before the torrent of water flowed through the city.

However, al-Ghaithi insisted on Wednesday that residents were informed ahead of the flooding.

‘We undertook all the precautions and informed the … the inhabitants of the areas the disaster could have taken place, we created an emergency room .. the security forces carried out their duty,” he said.

Additional reporting from Moutaz Ali in Tripoli