PORT-AU-PRINCE ? Desperate Haitians used corpses to set up roadblocks as anger and despair at the trickle of aid mounted on Friday and rotting bodies littered the streets after a massive earthquake killed tens of thousands of people.

The international Red Cross estimated 45,000 to 50,000 people were killed in Tuesday?s cataclysmic earthquake. The Haitian Red Cross said it believed 3 million more?one third of Haiti?s population?were hurt or left homeless by the 7.0-magnitude quake.

Haitian-born rap star Wyclef Jean called it ?the apocalypse.?

?We spent the day picking up dead bodies, all day that?s what we did,? he told Fox News. ?There?s so much bodies in the streets that the morgues are filled up, the cemeteries are filled up.?

More than 48 hours after the disaster, tens of thousands of people clamored for food and water and help while digging out relatives still missing under the rubble.

Shaul Schwarz, a photographer for TIME magazine, said he saw at least two downtown roadblocks formed with bodies of earthquake victims and rocks.

Angry survivors staged the protest at the sluggish distribution of aid to the traumatized victims.

?They are starting to block the roads with bodies. It?s getting ugly out there. People are fed up with getting no help,? Schwarz told Reuters.

?More doctors, fewer journalists,? one man yelled angrily, shaking his fists at a foreign media crew.

Stench of death

Harrowing scenes were being repeated across the city as frustrated Haitians dug with their hands through mountains of concrete and rubble while the screams and moans of those buried below rang out.

Hundreds of bodies, some mutilated and half-clothed, lay rotting outside the devastated central hospital as waves of distraught Haitians moved from corpse to corpse in search of their loved ones.

A stench of death hung over the capital Port-au-Prince as residents spent a third night in the open, rattled by aftershocks.

Logistical nightmare

Despite the launch of a massive global foreign aid operation, there was no sign of heavy lifting equipment among the ruins as tons of material and badly needed supplies clogged up the international airport.

Adding to the logistical nightmare were reports of looting and gunshots in the scramble for help, forcing some rescue crews to stop work at nightfall.

?If international aid doesn?t come, the situation will deteriorate quickly. We need water and food urgently,? said one survivor, Lucille.

Some 7,000 dead had already been buried by Thursday, Peru?s Prime Minister Velasquez Quesquen said from Port-au-Prince after Haitian officials earlier warned the overall toll may exceed 100,000.

Haitian Sen. Youri Latortue had told the Associated Press the death toll could reach 500,000.

Scuffles for food

At Port-au-Prince, planes jostled for space on the small airport?s tarmac and single runway as aid poured in from around the world, but the big problem was getting it to where it was needed most.

The United States has assumed air traffic control but flights were delayed as staff struggled to unload supplies.

Little aid had trickled down to the streets. An AFP video showed scuffles breaking out as a helicopter dropped food over one part of Port-au-Prince.

Sporadic gunshots could be heard, and witnesses said there had already been some looting in a city sadly familiar with bloodshed and natural disasters.

Moans from the rubble

In the agonizing wait for aid, residents dug through mountains of concrete, their efforts punctuated by the screams and moans of those trapped.

Governments around the world promised aid, donations rolled in by text message and the Internet while Hollywood idols lent their star power to appeal for funds.

China, France, Iceland, the United States and Venezuela were among nations with teams on the ground.

The aid coming in includes field hospitals, doctors, medicines, search-and-rescue teams with sniffer dogs, water and water purification equipment, food, tents, blankets, heavy lifting equipment as well as soldiers and experts.

Communications remained poor, and moving around was hampered by destroyed roads and lack of fuel.

Haitians were also angered they had had no word from their leaders.

Worst disaster in UN history

The United Nations said 36 of its staffers had been killed, in the worst disaster in the global body?s history. Another 188 were still missing.

The quake flattened buildings across entire hillsides and many people were still trapped alive in the rubble, with little sign of organized rescue efforts.

Relief workers warned the death toll would rise quickly if tens of thousands of injured Haitians, many with broken bones and serious loss of blood, did not get first aid in the next day or so.

Looters swarmed a collapsed supermarket in the Delmas area of Port-au-Prince, carrying out electronics and bags of rice unchallenged. Others siphoned gasoline from a wrecked tanker.

?All the policemen are busy rescuing and burying their own families,? said tile factory owner Manuel Deheusch. ?They don?t have the time to patrol the streets.?

The quake?s epicenter was only 16 kilometers from Port-au-Prince, a sprawling and densely packed city in a nation dogged by poverty, catastrophic natural disasters and political instability.

Dead peacekeepers

Rescuers who heard scratching sounds pulled a security guard from the UN headquarters building that had collapsed. Secretary General Ban Ki-moon said the crew located Tarmo Joveer, an Estonian guard, under 13 feet of rubble.

David Wimhurst, a spokesperson for the UN peacekeeping mission, said the dead included 19 UN peacekeepers, four international police officers and 13 civilians.

When the earthquake struck just before 5 p.m. Tuesday, Wimhurst said the entire headquarters building began ?shaking violently? and he was holding on to furniture ?to stop myself being thrown around the room.?

After the shaking subsided, he saw that the central part of the headquarters building had collapsed, blocking access to the outside. Eventually, about 15 people left the wrecked building by going out his window and down three stories on a ladder.

Life goes on

But while the silence of the dead was overwhelming in a city where bodies littered the streets in the 80-degree heat, life also went on.

Brazilian soldiers helped deliver a baby girl in an improvised garage-hospital at their base, just hours after the quake hit.

Capt. Fabricio Almeida de Moura said the child was doing well, but the life of the mother, who apparently went into labor from the shock of the tremor, was in danger from bleeding.