Port-au-Prince, Haiti — As Haitians drew close to the critical 72-hour mark after a devastating 7.0-magnitude earthquake, a sign of their desperation — a mass grave serving as possibly the final resting place of scores of victims — was discovered Friday outside Port-au-Prince.

At least 100 bodies were discovered by a CNN crew in one open pit outside the capital city, with several other pits half-filled or completely covered over with earth, presumably full. Survivors of the quake brought bodies to the site on plywood, wrapped in cloth, by dump trucks and, in one case, an old refrigerator. The stench of death overwhelmed the city.

Elsewhere, bodies were being shoved into old crypts in the city’s existing cemeteries.

Haiti’s Minister of Civil Protection said Friday that the government estimates more than 50,000 people were killed, with the number possibly closer to 100,000. There is not yet an official count of the dead from Tuesday’s earthquake.

Also on Friday, U.S. Homeland Security Secretary Janet Napolitano announced she is designating a temporary protected status for Haitian nationals who were in the United States as of Tuesday.

“This is a disaster of historic proportions and this designation will allow eligible Haitian nationals in the United States to continue living and working in our country for the next 18 months,” she said.

“Providing a temporary refuge for Haitian nationals who are currently in the United States and whose personal safety would be endangered by returning to Haiti is part of this administration’s continuing efforts to support Haiti’s recovery

Despite the death and destruction, hundreds of people, mostly women, took to the streets in an area of Port-au-Prince on Friday, singing and chanting as they marched down the street — a sign of resilience amid the mountains of rubble.

It is not the first time that such a display has been observed. Singing and clapping has been be heard well into the night in a large square that thousands of people have made home after the earthquake, a CNN crew reported.

Meanwhile, rescuers raced against a crucial 72-hour window of time to free those who still may be alive trapped under the remains of buildings while aid workers continued to trickle into the country, trying to provide water and food to survivors in the country’s rubble-strewn capital.

The quake toppled many of Port-au-Prince’s buildings, and U.N. Secretary-General Ban Ki-moon estimated Friday that it left as much as “50 percent of buildings in the worst-hit areas damaged or destroyed.”

Many of the capital’s 3 million people are without access to food, water, shelter and electricity, he said, and crews are working “to save as many lives as possible.”

The relief effort has been challenged by the destruction and the need for more supplies, he said, citing blocked roads and limited capacity at the capital’s one-runway airport. The Federal Aviation Administration ordered a ground stop on all U.S. flights into Haiti Friday because of a lack of ramp space.

But, he said, aid flights are arriving, and food and medical supplies are beginning to be distributed in Port-au-Prince.

“Although it is inevitably slower and more difficult than any of us would wish, we are mobilizing all resources as fast as we possibly can,” Ban said Friday, announcing an appeal for $550 million.

Ban listed the needs — food, water, “tents, and more tents” for shelter, medical supplies, medical personnel and heavy lifting equipment. He said the World Food Programme “is feeding around 8,000 people several times a day” and food distribution centers in the capital are being established that will offer ready-to-eat meals.

“Obviously, that is only a drop in the bucket in the face of the massive need,” he added, “but the agency will be scaling up to feed approximately 1 million people within 15 days and 2 million people within a month.”

Also on Friday, U.S. Homeland Security Secretary Janet Napolitano announced she is designating a temporary protected status for Haitian nationals who were in the United States as of Tuesday.

“This is a disaster of historic proportions and this designation will allow eligible Haitian nationals in the United States to continue living and working in our country for the next 18 months,” she said.

“Providing a temporary refuge for Haitian nationals who are currently in the United States and whose personal safety would be endangered by returning to Haiti is part of this administration’s continuing efforts to support Haiti’s recovery

The aircraft carrier USS Carl Vinson arrived off the country’s shore on Friday, carrying with it 19 helicopters, 51 hospital beds and three operating rooms. Impact Your World

Other assets include the destroyer USS Higgins for search and rescue and support, and Coast Guard cutters with helicopters. Adm. Michael Mullen, chairman of the Joint Chiefs of Staff, said the 82nd Airborne Division is arriving to help with security. Small helicopter-carrying naval vessels also will be arriving.

And, Mullen said, “the (USS) Bataan, with capabilities similar to those of Carl Vinson, will be accompanied by two other ships in her amphibious ready group, USS Fort McHenry and USS Carter Hall [both dock landing ships], and the Marines of the 22nd Marine Expeditionary Unit.”

And at the end of next week, the hospital ship Comfort is expected to be off the coast of Haiti. Haiti aid efforts hampered in critical hours

Throughout the city, people tried to cope as best they could amid now-common activities brought on by the disaster. In just a brief moment on one street, people carried an injured man on a makeshift stretcher as a severely injured woman lay on the sidewalk outside a first-aid treatment center. A truck bearing a coffin passed by, closely followed by a van carrying another injured person.

The United Nations announced Friday that at least 37 of its personnel had died — 36 with the U.N. mission and one with the World Food Programme. The number of unaccounted for people stands at 330. There are 12,000 people working for U.N. entities in Haiti.

As world agencies and countries marshaled their relief resources, President Obama spoke for about a half-hour with Haitian President Rene Preval on Friday, pledging the “full support of the American people,” including long-term help.

Preval said that he has been touched by the friendship of the American people.

“From the bottom of my heart and on behalf of the Haitian people, thank you, thank you, thank you,” he said. Watch how texting is helping to raise money for Haiti

He expressed his condolences for the loss of American citizens in Haiti, a toll that the State Department placed at six so far.

Rescue and recovery efforts have become top priorities for nations across the globe, and countries with poor relations have set aside their differences to help Haiti. Cuba is allowing the United States to use its airspace to fly medical evacuation flights, meaning planes carrying earthquake victims can take a straight-line route from Haiti to the United States, reducing the flight time.

In Russia, President Dmitry A. Medvedev announced the deployment of a rapid-response search-and-rescue team, dog teams, psychologists and doctors, special search equipment, including a lighting tower and powerful floodlights that will allow rescue operations to continue at night.

Despite relative calm, CNN reporters witnessed some sporadic looting and violence Thursday afternoon.

“If help doesn’t come quickly, it probably will [get worse],” Agnes Pierre-Louis, manager of her family-owned hotel, the Le Plaza in downtown Port-au-Prince. “We’re not hearing anything from the government. We’re not seeing any foreign aid yet.”

But Lt. Gen. Ken Keen, deputy commander of the U.S. Southern Command, said forces have not “seen a great deal of insecurity.” The priority now, he said, is cranking up rescue and relief efforts to stave off restiveness.

Secretary of Defense Robert Gates echoed that sentiment, saying that “other than some scavenging and minor looting, our understanding is the security situation is pretty good.”

“The key is to get the food and the water in there as quickly as possible so that people don’t, in their desperation, turn to violence or lead to the security situation deteriorating.”

This post was submitted by Anderson Cooper and Ivan Watson, CNN .