Time is running out for the thousands of people still trapped beneath the rubble and wreckage from the earthquake in Haiti, while many more thousands struggle to find adequate medical care.
Hospitals and relief workers already in Haiti report they are overwhelmed by the number of victims and are desperate for additional support.
The International Red Cross said a third of the country's 9 million people may need emergency aid. Red Cross volunteers on the ground have been providing first aid to victims but ran out of supplies Wednesday night.
"The limited medical supplies that the Red Cross had in Haiti before the earthquake have now been distributed and exhausted," American Red Cross spokesman Eric Porterfield told ABC News. Thirty relief workers left Santo Domingo at 4 a.m. local time today to travel to Haiti with additional medical supplies.
Haitian Red Cross spokesman Pericles Jean-Baptiste told Reuters that "There are too many people who need help," and former president Bill Clinton said that some places don't even have aspirin.
A doctor with the aid organization Partners in Health tweeted that it had been "getting overwhelmed in terms of wounded coming from [Port-au-Prince]. Will need orthopedic support as well."
Partners in Health has set up mobile clinics in Port-au-Prince and has hospitals about two hours outside the city. On its Web site, the organization is asking for volunteer "surgeons (especially trauma/orthopedic surgeons), ER doctors and nurses, and full surgical teams (including anesthesiologists, scrub and post-op nurses and nurse anesthetists)."
The devastating earthquake in Haiti only added to the humanitarian crisis in a nation where 80 percent of the population lives below the poverty line. ABC News' senior health and medical editor Dr. Richard Besser said Wednesday that the rescue and recovery effort would be especially complicated and difficult.
The Caribbean nation already has "some of the worst health indicators in the world," Besser said, and has a limited ability to absorb this kind of a catastrophe. Haiti is the poorest country in the Western Hemisphere, and the population of 9 million already faces high rates of tuberculosis, HIV/AIDS, viral and respiratory disease.
According to the U.S. Agency for International Development, Haiti has the highest per capita tuberculosis burden in the Latin American and Caribbean region. After HIV/AIDS, TB is the country's greatest infectious cause of mortality.
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Besser said that medical aid would be one of the most important parts of the aid effort, because Haiti's health care capacity was already very limited before the quake. The U.S. is preparing the hospital ship the USS Comfort for possible deployment to the region.
"Access to quality care didn't exist before this earthquake," he said. "It doesn't exist now, so what's important is arranging evacuations and setting up hospitals. ... There's not a lot of time to save the most critically injured."
Besser said that the first 36 hours after a disaster is the most critical period, but that during these first few days "communities tend to have to take care of themselves."
The Associated Press is reporting that Haitians are doing just that -- using pick-up trucks as makeshift ambulances and doors as stretchers to transport victims.