GEOFF BENNETT: The deadly floods that inundated Eastern Libya earlier this week have now led to a tide of the dead, bodies seemingly everywhere, with a death toll of more than 11,000, and a race that pits dignity and respect for those lost against the threat of disease and further calamity.

Stephanie Sy reports.

STEPHANIE SY: Saad Rajab's home in the city of Soussa is submerged in layers of mud and completely unlivable.

SAAD RAJAB MOHAMMED AL HASSI, Flood Survivor (through translator): It's not easy for a man to go through this.

Only God knows what we are going through.

Even the government did not help us.

We are left out on the streets.

STEPHANIE SY: But the streets of Derna, about 60 miles east of him, have sustained the most damage.

Thousands are still believed to be missing, and as much as a quarter of the city has been washed away.

For the fifth day straight, local and international rescue teams continued to search the rubble and wade through the waters.

Libyan authorities today sealed off most of the city and said only rescue teams would be allowed to enter the worst-hit areas.

Libyans are now racing to bury their dead, but there aren't enough body bags; 5,000 from the Red Cross shipped out today.

What to do with the bodies is a pressing question.

The World Health Organization called on authorities to stop burying flood victims in mass graves.

The U.N. says at least 1,000 bodies have been buried that way, which experts warn could lead to further trauma for family members.

BILAL SABLOUH, International Committee of the Red Cross: Graves need to be mapped, so there is record of who is buried there.

The efforts make it possible for loved ones to later recover the body and had the closure of a private burial.

STEPHANIE SY: For the living, critical aid supplies are coming in, but with damaged roads and bridges, access to Derna remains difficult.

Local authorities say a sea corridor could be established to deliver urgent relief.

Martin Griffiths is the U.N.'s top humanitarian official.

MARTIN GRIFFITHS, U.N. Undersecretary-General for Humanitarian Affairs and Emergency Relief Coordinator: Priority areas are shelter, food, key primary medical care because of the worry of cholera.

STEPHANIE SY: But aid groups accuse the government of a lack of central oversight.

Even before the disastrous flood, at least 300,000 Libyans were already in desperate need of aid.

The U.N. has launched a $71.4 million appeal for the hundreds of thousands more now reeling from the floods.

As appeals for help go out, prayers are lifted up.

Hundreds of survivors filled a mosque still standing in Derna, grieving, but not without faith.

For the "PBS NewsHour," I'm Stephanie Sy.