Anger and despair has mounted in quake-hit Haiti with scores facing a third night trapped beneath the ruins, food and water running out, and little sign of international aid.
The stench of death from decomposing bodies strewn in the streets hung over the capital of Port-au-Prince as residents hunkered down for another night in the open, traumatized by aftershocks triggered by Tuesday's 7.0-magnitude earthquake.
Despite a massive aid operation, there was no sign of heavy lifting equipment among the rubble even as tons of material and badly-needed supplies deluged the international airport.
Media reported people have started blocking roads with corpses in Haiti's capital Port-au-Prince to protest against the delay in emergency aid.
TIME magazine photographer Shaul Schwarz said he saw at least two downtown roadblocks formed with bodies of earthquake victims and rocks.
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"They are starting to block the roads with bodies; it's getting ugly out there," he said. "People are fed up with getting no help."
Haitian officials have warned the overall death toll may top 100,000 and say three million people could have been affected by the powerful quake that ripped across the poorest nation in the Americas.
Red Cross says up to 50,000 dead
The quake has killed between 40,000 to 50,000 people, according to figures provided by the International Red Cross.
"If international aid doesn't come, the situation will deteriorate quickly. We need water and food urgently," said Haitian survivor Lucille, still dazed by the scenes of devastation and carnage on the Caribbean island nation.
Gunshots, reports of looting
Sporadic gunshots were heard, and witnesses said there had already been some looting in a city that has seen bloodshed and violence over the past decades.
"More doctors, fewer journalists," one man yelled out angrily, shaking his fists at a foreign media crew.
Aid trickles in from 30 countries
Eight search-and-rescue teams comprising some 260 people were on the ground, and 30 countries had pledged or already sent help, US State Department spokesman P.J. Crowley said, adding they were already pulling survivors from the ruins.
China, France, Iceland, the United States and Venezuela were among those with teams on the ground, with Washington sending ships, helicopters, planes, rescue teams, a floating hospital and more than 5,000 troops.
"Not only is the United States' commitment to Haiti growing, but also the international commitment as well," said Crowley.
US takes over air traffic control
The United States had also taken over air traffic control at the swamped airport which was now operating round-the-clock, he said. Flights were delayed though as staff struggled to unload supplies. And little aid had trickled down onto the streets.
An AFP video showed scuffles breaking out as a helicopter dropped food over part of the city. Haitians were also angered they had had no word from any of their leaders.
One group trying to free a man trapped in the rubble of the tax office looked up wearily at the planes flying overhead.
"We hear on the radio that rescue teams are coming from the outside, but nothing is coming.
We only have our fingers to look for survivors," said Jean-Baptiste Lafontin Wilfried. More than 48 hours after the quake, Haitians were still digging by hand through mountains of concrete and rubble while the screams and moans of those buried below rang out.
Dozens of people rescued
Dozens of people were rescued thanks to frantic efforts and as sniffer dogs began to comb the ruins.
They included Estonian police officer Tarmo Joveer pulled virtually unharmed from the rubble of the UN headquarters by a specialized US rescue team from Virginia.
But the moments of joy were few, compared to the death and destruction stalking the city.
"It's a small miracle," UN chief Ban Ki-moon said at the United Nations in New York, as he revealed that 36 UN staffers had been killed, in the worst disaster in the global body's history. Another 188 were still missing.
Obama pledges $US100 million in aid
US President Barack Obama sought to lift up a despairing people, facing acute shortages of food, water and shelter, offering $US100 million ($A107.41 million) in immediate assistance.
"To the people of Haiti, we say clearly and with conviction, you will not be forsaken, you will not be forgotten," he said.
Obama and French President Nicolas Sarkozy, along with Brazil and Canada and other concerned nations are planning to hold an international conference on Haiti's reconstruction, the French presidency said. "People throughout the world want to help," said Ban.
"One of our biggest challenges will be to help them to help Haiti to the utmost," he warned, as communications remained poor, and moving around was hampered by destroyed roads and lack of gasoline.
A first contingent of US troops was headed to Haiti, and the USS Carl Vinson aircraft carrier was to arrive later in the day with destroyers and more Coast Guard ships en route and 5,000 troops on stand-by.
But lacking heavy lifting equipment, harrowing scenes were being repeated across the city as frustrated workers dug with hands and simple tools to reach the trapped.
Some people set up temporary shelters with sheets and covers in a public square, while others were trekking out carrying meagre belongings, searching for safer places outside the city.
