MANILA -- The Philippines was still trying to comprehend the destruction that Typhoon Haiyan brought to this string of islands in the Pacific on Sunday.
Rescue and relief efforts were having trouble getting to the scene of the most damage, such as Tacloban, where even the Red Cross saw its offices damaged.
Read: American Red Cross Provides Support For Philippines
"This area has been totally ravaged," said Sebastien Sujobert, head of the International Committee of the Red Cross in Tacloban. "Many lives were lost, a huge number of people are missing, and basic services such as drinking water and electricity have been cut off," he said.
Corpses hung from tree branches and were scattered along sidewalks and among flattened buildings. People raided grocery stores and gas stations in search of food, fuel and water.
As many as 10,000 people may have died when one of the most powerful typhoons ever recorded destroyed entire villages and devastated cities with huge waves and winds of nearly 150 mph.
A weakened but still powerful Haiyan was churning through the South China Sea and made landfall in northern Vietnam, which evacuated tens of thousands of people.
At the White House, President Obama said he and his wife Michelle said they are "deeply saddened'' by the death and damage in the Philippines and said the United States is assisting relief and recovery efforts. He praised the country's people for "incredible resiliency.''
In the Philippines, authorities were still trying to get to islands that no one had been able to communicate with since the typhoon struck Friday. But those areas reached revealed immense damage to homes, roads and buildings.
Frantic relatives crowded into the Villamor Air Base in Manila to wait for transport planes that were rescuing people from at least six of the archipelago's more than 7,000 islands that were hit hardest.
Maritess Tayag, in her 40s, and her sister, Maryann, 29, arrived at the airport dizzy, shaken and thirsty but elated to be alive. They came from their home in Tacloban on the island of Leyte, one of the hardest hit.
"I was in the house - trapped in my room. The water is up to my nose - I cannot breathe anymore. I am trying to save myself," said Maritess Tayag, describing the early hours of Saturday when ceaseless wind drove dark seawater mixed with foul-smelling water from canals higher and higher into their homes.
Her brother was in the house, too, trying to keep his head above the rising water, she said. But, "It reached up over his head. Then a big wave of fast flood reached up higher.
"I feel I would die at this moment because I can't - I don't know what I will do," Tayag said, crying.
Her younger sister and sister-in-law made it to the roof. Her brother and mother did not, she said, and both are probably dead.
Maryann Tayag described their town as looking as if it was a "World War II city" and said everyone was trying to flee in fear.
"It was almost a stampede at the airport in Tacloban," she said. "Everyone was trying to get on the plane. It's really, really terrible."
It was not until Sunday that authorities communicated with Leyte island. The sisters said there was no power or phone service. They said they saw looting everywhere. Food and water are almost non-existent, they said.
"It's all washed out ... including the hospitals and malls, by the strong winds and floods that came," Maritess Tayag said.
"The hardest thing is ... seeing your mother floating in the flood and you don't know what to do. You just see there and the only thing is you have to save yourself," Maryann Tayag said. "I could not save her because she drowned already, and it was not just water from the sea but mixed with dirty water - color black, like it came from river and smell like canal."
Regional Police Chief Elmer Soria said he was briefed by Leyte provincial Gov. Dominic Petilla late Saturday and told there were about 10,000 deaths on the island, mostly by drowning and collapsed buildings. The governor's figure was based on reports from village officials in areas where Typhoon Haiyan hit Friday.
Tacloban city administrator Tecson Lim said that the death toll in the city "could go up to 10,000." A mass burial was planned Sunday in Palo town near Tacloban.
After two days with no news from her family, elementary teacher Cherry Gonzaga left her home in Manila for Cebu for a late-night ferry to Leyte island.
"There's no way to get through to them, and my entire family is there, 15 people," said Gonzaga, 24, as she waited for tickets at a pier with dozens of other Filipinos desperate to learn their relatives are safe.
If the typhoon death toll is confirmed, it would be the deadliest natural catastrophe on record in the Philippines, topping both the 5,100 killed by Tropical Storm Thelma in November 1991 and the 5,791 killed after a magnitude-7.9 earthquake triggered a tsunami in the Moro Gulf in the southern Philippines in 1976.
In Washington, Defense Secretary Chuck Hagel directed the U.S. military's Pacific Command to deploy ships and aircraft to support search-and-rescue operations and airlift emergency supplies.
Philippine President Benigno Aquino III flew over Leyte by helicopter on Sunday and landed in Tacloban to get a firsthand look at the disaster. He said the government's priority was to restore power and communications in isolated areas and deliver relief and medical assistance to victims.
Defense Secretary Voltaire Gazmin said Aquino was "speechless" when he told him of the devastation in Tacloban.
"I told him all systems are down," Gazmin said. "There is no power, no water, nothing. People are desperate. They're looting."
In Vietnam, emergency responders are shifting gears as Haiyan's forecasted path has moved northward, leaving residents in the central part of the country breathing a sigh of relief.
Francis Markus, spokesman for the Red Cross in Vietnam said that the unpredictable trajectory of the storm has stretched the country's emergency response resources thin, creating new challenges as preparations have shifted from the center to the north of the country.
And while the central area was spared the brunt of Haiyan, Vietnam remained on high alert as the deadly typhoon neared.
"We don't really have an idea of the severity with which this northern region is going to be hit," Markus said. "I think everybody's been very shocked by the horror of the impact of Haiyan in the Philippines and it means we really have to do the maximum to prepare for it in Vietnam and in China and certainly not be complacent."
Contributing: Tom Maresca from Ho Chi Minh City; Doyle Rice from McLean, Va.; and the Associated Press