At least 1000 bodies have already been recovered in the city of Derna alone, and officials expect the death toll will be much higher, after storm Daniel barrelled across the Mediterranean into a country crumbling from more than a decade of conflict.
A Reuters journalist on the way to Derna, a coastal city of around 125,000 inhabitants, saw vehicles overturned on the edges of roads, trees knocked down, and abandoned, flooded houses.
A minister in the administration that controls the east said the situation in Derna is "disastrous".
"Bodies are lying everywhere - in the sea, in the valleys, under the buildings," Hichem Abu Chkiouat, minister of civil aviation and member of the administration's emergency committee, told Reuters by phone.
"The number of bodies recovered in Derna is more than 1000," he said. "I am not exaggerating when I say that 25 per cent of the city has disappeared. Many, many buildings have collapsed."
Abu Chkiouat later told Al Jazeera he expected the total number of dead across the country to reach more than 2500, as the number of missing people was rising.
Some 10,000 people were estimated missing.
"We can confirm from our independent sources of information that the number of missing people is hitting 10,000 so far," Tamer Ramadan, the head of a delegation of the International Federation of the Red Cross and Red Crescent Societies (IFRC), told reporters in Geneva via video link from Tunisia.
Videos showed a wide torrent running through Derna's city centre after dams burst. Ruined buildings stood on either side.
Another video shared on Facebook, which Reuters could not independently verify, appeared to show dozens of bodies covered in blankets on the pavements.
Convoys of aid and assistance were heading towards the city.
Libya is politically divided between east and west and public services have crumbled since a 2011 NATO-backed uprising that prompted years of conflict.
The internationally recognised government in Tripoli does not control eastern areas but has dispatched aid to Derna, with at least one relief flight leaving from the western city of Misrata on Tuesday, a Reuters journalist on the plane said.
Other countries, including the United States, also said they would help.Â
