Aid was trickling into eastern Libya on Wednesday, where more than 5,000 people have died in recent days from catastrophic flooding. But with roads and bridges damaged and cut off, access to the hardest-hit city of Derna on the Mediterranean coast remained a major hurdle to bringing in help, according to international aid groups.

Thousands of people are believed to still be missing, meaning the death toll was likely to rise further in the hours and days ahead.

The flooding hit after heavy rains burst through two dams near Derna, a city of nearly 100,000 people. Much of the city was destroyed, and entire neighborhoods, including homes, schools and mosques, were swept away in the flooding that began over the weekend. The Derna City Council has called for the opening of a maritime passageway to the city and for urgent international intervention.

The Libyan Red Crescent, a nonprofit aid group whose volunteers have helped evacuate residents and which is leading the search and rescue efforts, reported early Wednesday on its Facebook page that for a third day, its volunteers are searching for some of the thousands still missing, combing fields, trails and riverbanks.

“No missing persons have been found at this moment,” the group said.

The group published a document on its Facebook page listing the survivors from Derna. By Wednesday morning, it continued to grow to more than 230 names.

“The support is trickling in. We just need more of it,” said Dax Bennet Roque, the Norwegian Refugee Council’s country director for Libya. “The response in Libya for so long has been underfunded. There’s an urgent need for international help.”

He welcomed the United Nations’ announcement that it was allocating $10 million from its emergency response fund to help those affected by the floods.

By Wednesday, it was still unclear how much of the aid — both from inside Libya and internationally — had arrived in the most-affected areas.

Shipments of supplies, including body bags and medical equipment, left early Tuesday morning from the Libyan capital Tripoli, in the western half of the politically divided country, for the city of Benghazi, ​​the main city on the eastern side, the government in Tripoli said. A medical convoy of doctors, nurses and other rescue volunteers had already arrived in Benghazi on Tuesday morning, it added.

What was most needed, the Tripoli government said, was rescue workers and inspectors and others who specialize in handling flood situations.

Rescue teams sent by Turkey and the United Arab Emirates arrived in Benghazi on Tuesday, according to the Libyan television channel al-Masar. But Benghazi is more than 180 miles from Derna by road, and access into the city had been cut off by the flooding.

“The infrastructure has been destroyed, which makes it very difficult for emergency medical workers to reach these areas,” said Basheer Omar, spokesman for the International Committee of the Red Cross in Libya. He added that local authorities had to disable the electrical grid for fear of people being electrocuted in the floods.

His organization has been sending supplies and technical support to the Libyan Red Crescent, including body bags and personal protective gear.

“These areas are totally disconnected, there are no phones, no food, no electricity, so the situation is really dire in these areas,” he said. “It’s beyond the capacity of the authorities in Libya, so Libya needs the support of the international community.”