More than 1,000 people were killed and at least 10,000 were missing in Libya in floods caused by a huge Mediterranean storm that burst dams, swept away buildings and wiped out as much as a quarter of the eastern coastal city of Derna.

Officials expected the death toll to rise much higher after Storm Daniel barrelled across the Mediterranean into a country divided and crumbling after more than a decade of conflict.

In Derna, a city of around 125,000 inhabitants, Reuters journalists saw wrecked neighbourhoods, their buildings washed out and cars flipped on their roofs in streets covered in mud and rubble left by a wide torrent after dams burst.

More than 1,000 bodies have already been recovered in Derna alone. Bodies were lined up on the street outside a crowded hospital, with residents looking under the shrouds covering them in search of loved ones.

Similar devastation reigned on the way into Derna, with vehicles overturned on the edges of roads, trees knocked down and houses inundated and abandoned.

"Bodies are lying everywhere - in the sea, in the valleys, under the buildings," Hichem Abu Chkiouat, minister of civil aviation in the administration that controls the east, told Reuters by phone shortly after visiting Derna.

"The number of bodies recovered in Derna is more 1,000," he said. "I am not exaggerating when I say that 25% of the city has disappeared. Many, many buildings have collapsed."

Abu Chkiouat later told Al Jazeera that he expected the total number of dead across the country to reach more than 2,500, as the number of missing people was rising.

Other eastern cities including Libya's second biggest city Benghazi, were also hit by the storm, and Tamer Ramadan, head of a delegation of the International Federation of the Red Cross and Red Crescent Societies, said the death toll would be "huge".

"We can confirm from our independent sources of information that the number of missing people is hitting 10,000 so far," he told reporters via video link.

United Nations aid chief Martin Griffiths said in a post on X, formerly known as Twitter, that emergency teams were now being mobilised to help on the ground.

As Turkey and other countries rushed aid to Libya, including search and rescue vehicles, rescue boats, generators and food, distraught Derna citizens rushed home in search of loved ones.

In Derna, Mostafa Salem, 39, said he had lost 30 of his relatives. "Most people were sleeping. Nobody was ready," Salem told Reuters. As the storm had intensified into the evening, he said, people started getting alerts saying that the water level at one of the dams was rising and noises were emanating from it.

At Tripoli airport in northwest Libya, a woman started to wail loudly as she received a call saying most of her family were dead or missing. Her brother-in-law, Walid Abdulati, said "we are not speaking about one or two people dead, but up to 10 members of each family dead".

Karim al-Obaidi, a passenger on a plane from Tripoli to the east, said: "I have never felt as frightened as I do now ... I lost contact with all my family, friends and neighbours."

An interior ministry spokesperson told Al Jazeera that naval teams were searching for the "many families that were swept into the sea in the city of Derna". Footage broadcast by Libyan TV station al-Masar showed people searching for bodies and men in a rubber boat retrieving one from the sea.

"We have nothing to save people ... no machines...we are asking for urgent help," said ambulance worker Khalifah Touil.

Flood warning
Derna is bisected by a seasonal river that flows from highlands to the south, and normally protected from flooding by dams.

A video posted on social media showed remnants of a collapsed dam 11.5 km (7 miles) upstream of the city where two river valleys converged, now surrounded by huge pools of mud-coloured water.

"There used to be a dam," a voice can be heard saying in the video. Reuters confirmed the location based on the images.

In a research paper published last year, hydrologist Abdelwanees A. R. Ashoor of Libya's Omar Al-Mukhtar University said repeated flooding of the seasonal riverbed, or wadi, was a threat to Derna. He cited five floods since 1942, and called for immediate steps to ensure regular maintenance of the dams.

"If a huge flood happens the result will be catastrophic for the people of the wadi and the city," the paper said.

Pope Francis was among world leaders who said they were deeply saddened by the deaths and destruction in Libya.

Libya is politically split between east and west and public services have fallen apart since a 2011 NATO-backed popular uprising that prompted years of factional 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.

Norway's Refugee Council said tens of thousands of people were displaced with no prospect of going back home.