Aid and assistance slowly made its way to Haitians left without basic necessities by this week's earthquake, though relief efforts were further complicated by aftershocks and the threat of looting and violence.
A magnitude-4.5 aftershock shook the capital of Port-au-Prince shortly before noon Saturday, raising new fears of damage. Rescue crews continued to work to free people believed trapped under rubble, while others carried out the grim task of disposing of the countless dead.
Secretary of State Hillary Clinton landed Saturday in Haiti to meet with President Rene Preval, and the U.S. is sending more food, water and relief supplies. But it wasn't clear when that and other aid will reach all those in need.
"We are here at the invitation of your government to help you," she said at a news conference at the Port-au-Prince airport. "As President Obama has said, we will be here today, tomorrow and for the time ahead. And speaking personally, I know of the great resilience and strength of the Haitian people. You have been severely tested. But I believe that Haiti can come back even stronger and better in the future."
Clinton's remarks appeared designed to counter any notion of a too-intrusive American involvement in the aftermath of the quake, while also assuring Haitians the humanitarian mission would continue as long as it's needed.
The secretary of state is also bringing 50 American evacuees back with her.
About 600,000 humanitarian daily rations — basic nutrition packages that provide 2,300 calories — were expected to be at Haiti's airport by Saturday evening, said Tim Callaghan, the White House adviser helping to oversee relief efforts in Haiti. The World Food Program plans to distribute the rations.
Callaghan told reporters on a conference call Saturday that water purification units arrived Friday night, and officials hope they will produce up to 300,000 liters of water. More water is coming from the neighboring Dominican Republic.
Denis McDonough of the National Security Council said 180 tons of relief supplies had arrived in Haiti, but he didn't know how much had been distributed or where it has gone. "We don't have a good breakdown," he said.
The aftershock Saturday morning, though strong, did not appear strong enough to cause much damage, U.S. geophysicist Paul Caruso said, though even a small quake could bring down buildings hurt by Tuesday's magnitude-7.0 quake.
The latest tremors come amid a report from the U.S. embassy in Port-au-Prince of increased lootings, carjackings and armed attacks, while police seem absent in the area.
There has been little sign of any aid in much of the city four days after the quake.
A water delivery truck driver said he was attacked in one of the city's slums. There were reports of isolated looting as young men walked through downtown with machetes, and robbers reportedly shot one man, whose body was left on the street.
"I don't know how much longer we can hold out," said Dee Leahy, a lay missionary from St. Louis, Missouri, who was working with nuns handing out provisions from their small stockpile. "We need food, we need medical supplies, we need medicine, we need vitamins and we need painkillers. And we need it urgently."
Clinton on Friday cited a "race against time" before anxiety and anger create additional problems. Relief workers warned that unless supplies are quickly delivered, Port-au-Prince will degenerate into lawlessness.
The U.S. Southern Command said it now has 24 helicopters flying relief missions — many from warships off the coast — with 4,200 military personnel involved and 6,300 more due by Monday.
The Red Cross estimates 45,000 to 50,000 people were killed in the earthquake. While workers are burying some in mass graves, countless bodies remain unclaimed in the streets and the limbs of the dead protrude from crushed schools and homes.
Haiti's government alone has already recovered 20,000 bodies — not counting those recovered by independent agencies or relatives themselves, Prime Minister Jean-Max Bellerive told The Associated Press. He said a final toll of 100,000 dead would "seem to be the minimum."
The U.N. has confirmed the body of Haiti mission chief Hedi Annabi was found in the rubble of its collapsed headquarters.
Other bodies were thrown into trucks and driven to the outskirts of town to be burned Friday. Residents paint toothpaste around their nostrils and beg passers-by for surgical masks to cut the smell.
A third of Haiti's 9 million people may be in need of aid. U.N. Secretary-General Ban Ki-moon said the World Food Program was providing high-energy biscuits and ready-to-eat meals to around 8,000 people "several times a day."
"Obviously, that is only a drop in the bucket in the face of the massive need, but the agency will be scaling up to feed approximately 1 million people within 15 days and 2 million people within a month," he said.
U.S. officials on Friday also acknowledged the limits of their initial relief efforts, and promised a quick ramp-up in delivery of badly needed supplies. Dr. Rajiv Shah, the White House's coordinator of the U.S. relief effort who was also expected to arrive Saturday, indicated aid would begin flowing more freely in the next few days.
The effort to get aid to the victims has been stymied by blocked roads, congestion at the airport, limited equipment and other obstacles. U.N. peacekeepers patrolling the capital said popular anger was rising and warned aid convoys to add security to guard against looting.
The International Red Cross said a big medical convoy has entered Haiti by road Saturday from the Dominican Republic because of the backups at the airport, but still remains several hours away from arriving in Port-au-Prince
"It's not possible to fly anything into Port-au-Prince right now. The airport is completely congested," spokesman Paul Conneally told The Associated Press by phone from the Dominican capital, Santo Domingo.
Conneally said the convoy was carrying a 50-bed field hospital, surgical teams and an emergency telecommunications unit. In Geneva, Red Cross spokesman Matthew Cochrane said two larger field hospitals will arrive later.
The World Health Organization has said eight hospitals in Port-au-Prince were destroyed or damaged, severely curtailing treatment available for the injured.
Officials said damage to the seaport also is a problem for brining in aid. The arrival Friday of the aircraft carrier USS Carl Vinson started helping immediately, taking pressure off the city's jammed airport. Within hours, an 82nd Airborne Division rapid response unit was handing out food, water and medical supplies from two cargo pallets outside the airport.
Others tried to help in smaller ways.
Milero Cedamou, the 33-year-old owner of a small water delivery company, twice drove his small tanker truck to a tent camp where thousands of homeless people are living. Hundreds clustered around to fill their plastic buckets.
"This is a crisis of unspeakable magnitude, it's normal for every Haitian to help," Cedamou said. "This is not charity."
Medical teams from other nations set up makeshift hospitals to tend to the critically injured. Time, however, was running short for the rescue of people who still might be alive under the rubble.
The Associated Press contributed to this article