Two-year-old Redjeson Hausteen Claude reacts to his mother, Daphnee Plaisin, after he is rescued Thursday night from a collapsed home by Belgian and Spanish rescuers in the aftermath of the powerful earthquake in Port-au-Prince. A 7.0-magnitude earthquake struck Haiti on Tuesday, and time is running out to rescue anyone who may still be trapped alive in the many buildings.

Port-au-Prince, Haiti ? Pushed to the far edge of desperation, earthquake-ravaged Haitians dumped decaying bodies into mass graves and begged for water and food Friday amid fear that time is running out to avoid chaos and to rescue anyone still alive in the wreckage.

The U.S. military brought some relief, taking control of the airport, helping coordinate flights bringing in aid and evacuating foreigners and the injured. Medical teams, meanwhile, set up makeshift hospitals, workers started to clear the streets of corpses and water was being distributed in pockets of the city.

But the task was enormous.

Aid workers and authorities warned that unless they can quickly get aid to the people, Port-au-Prince will degenerate into lawlessness.

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. Survivors also fought one another for food pulled from the debris.

“I’m getting the sense that if the situation doesn’t get sorted (out) real soon, it will devolve into chaos,” said Steve Matthews, a veteran relief worker with the Christian aid organization World Vision.

Time also was running out to rescue anyone who may still be trapped alive in the many buildings in Port-au-Prince that collapsed in Tuesday’s magnitude-7.0 quake.

“Beyond three or four days without water, they’ll be pretty ill,” said Dr. Michael VanRooyen of the Harvard Humanitarian Initiative in Boston. “Around three days would be where you would see people start to succumb.”

An Australian TV crew pulled a healthy 16-month-old girl from the wreckage of her house Friday — about 68 hours after the earthquake struck. In a collapsed house, neighbors and reporters heard a cry and found an air pocket: part of the top floor had been held up by a cabinet.

“I could see a dead body that was there, sort of on top of the cabinet; I could hear the baby on the left side of the body screaming,” said David Celestino of the Dominican Republic, who had been working with the TV crew.

Although her parents were dead, Winnie Tilin survived with only scratches and soon was in the arms of her uncle, whose pregnant wife also was killed.

“I have to consider her like my baby because mine is passed,” Frantz Tilin told The Associated Press.

As temperatures rose into the high 80s, the sickly smell of the dead lingered over Port-au-Prince, where countless bodies remained unclaimed in the streets. Hundreds of bloated corpses were stacked outside the city morgue, and limbs of the dead protruded from crushed schools and homes.

At a cemetery outside the city, trucks dumped bodies by the dozens into a mass grave. Elsewhere, people pulled a box filled with bodies along a road, then used a mechanical front-loader to lift the box and tip it into a large metal trash bin. South of the capital, workers burned more than 2,000 bodies in a trash dump.

The Red Cross estimates 45,000 to 50,000 people were killed. A third of Haiti’s 9 million people may be in need of aid. As many as half of the buildings in the capital and other hard-hit areas were damaged or destroyed, according to the United Nations.

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. Secretary of State Hillary Rodham Clinton said she would go to Haiti today to inspect the damage and meet with President Rene Preval and other officials. Clinton, who will travel with USAID Administrator Dr. Rajiv Shah, said she wants to convey “our long-term, unwavering support, solidarity and sympathies.”