People whose homes were swept away by flooding in Libya’s eastern city of Derna a week ago faced the dilemma on Sunday of whether to stay despite a lack of fresh water or flee through areas where landmines have been displaced by the torrents.

Thousands of people are feared to have died after two dams above Derna broke on September 10, bringing down residential blocks lining a usually dry river bed as people slept. Many bodies were washed out to sea and more than 1,000 have already been buried in mass graves, according to the United Nations.

Sunrise on Sunday revealed a scene of quiet devastation, with piles of rubble cleared to the sides of empty roads along with tangled metal including pieces of wrecked cars.

Hamad Awad sat on a blanket on an empty street with a bottle of water and bedding alongside him.

“I am staying in our area trying to clean it and trying to verify who is missing,” he said. “Thank God for giving us patience.”

Entire districts of Derna, with an estimated population of at least 1,20,000, were swept away or buried in mud. State media said on Sunday at least 891 buildings had been destroyed in the city, whose mayor has said 20,000 people may have died.

Another resident said people were at a loss over what to do next.

“We still do not know anything, we are hearing rumours, some are trying to reassure us, others are saying you need to leave the city or stay here. We have no water and no resources,” said the resident, who gave just one name, Wasfi.

A report by the UN’s Office for the Coordination of Humanitarian Affairs (OCHA) said Libyan authorities had detected at least 55 children poisoned from drinking polluted water in Derna, where the homeless were surviving in makeshift shelters, schools or packed into the houses of relatives or friends.

Floodwaters had shifted landmines and other ordnance left over from years of conflict, posing an extra risk to the thousands of displaced people on the move, it said.

Aid organisations have flown in emergency aid and some countries have sent supplies, although international aid officials say much more help is needed.

“People came with aid from all over, and this made it easier on us, and we felt that we are not alone,” said Derna resident Hassan Awad as civil protection workers from Algeria searched the rubble of multi-storey buildings in the city for survivors.

Awad pointed to a rusty pole stretched between two buildings and said clinging to it was how his family had survived the flood which tore through their home, covering everything in mud.

In al Badya, a coastal settlement west of Derna, the hospital was treating victims from Derna as well as its own. Doctors built makeshift dams in the street when the flooding hit to try to hold back the water, but it rose within the building.

“This affected machinery and the infrastructure of the lower level of the hospital,” the hospital’s head, Abdel Rahim Mazek, said.