According to Martin Cottingham, a spokesman for Islamic Relief, the destruction in some areas is so complete that aid workers have walked for hours and not seen a single standing building.
"Telecommunications are down, impassible roads are blocked with collapsed buildings, fallen trees, and gridlock," he said.
Police and soldiers are struggling to keep order across the region amid widespread looting and reports of armed gangs roaming the streets.
Tacloban's mayor, Alfred Romualdez, urged residents to flee the city because local authorities were having trouble providing food and water and maintaining order, The New York Times reported. He said the city was in desperate need of trucks to distribute relief shipments that were accumulating at the city's airport as well as equipment to pull decaying corpses from the rubble.
The precarious security also worries humanitarian workers.
"The Tacloban team is facing enormous constraints because we cannot move around freely due to the security situation," said Elisabeth Byrs of the World Food Program, which is coordinating logistics for the aid and recovery effort.
Krista Armstrong of Save the Children, which is waiting for 100 tons of aid and four mobile health units to land in Cebu on Thursday morning, called on the government of the Philippines to help make sure humanitarian workers could do their jobs.
"We want the government to do all it can and step up its efforts to clear roads and improve security," she said.
Desperation triggered anarchy in communities flattened by the typhoon, and police were working to keep order across the region.
Eight people were crushed to death as thousands of people stormed a rice warehouse in Alangalang and carted away up to 100,000 sacks of rice, National Food Authority spokesman Rex Estoperez told The Associated Press.
Soldiers sent to restore order also fired into the air to scatter crowds scavenging through the ruins in Tacloban, where an NBC News crew spotted dozens of uncollected bodies in the streets on Wednesday.
Standing amid the rubble, Jennica Ekaya told the BBC that survivors were only looking for food.
"We can survive without these houses ... we'll sleep anywhere. But we need food. Only food," she said. "No money, no places, no televisions, no cellphones, no technology. Food, we need food."