PORT-AU-PRINCE, Haiti - Death was everywhere Wednesday in this devastated city of 2 million. Bodies of tiny children were piled next to schools. Corpses of women lay on the street with stunned expressions frozen on their faces as flies began to gather. Bodies of men were covered with plastic tarps or cotton sheets.

Moreover, untold numbers were still trapped after a powerful earthquake Tuesday crushed thousands of structures — from schools and shacks to the National Palace and the local U.N. headquarters.

As nations around the world mobilized to send help, Haitian Prime Minister Jean-Max Bellerive told Reuters that he believed the casualties would be "in the range of thousands of dead."

Soon after, however, Bellerive told CNN that "I believe we are well over 100,000" dead, while Haitian Sen. Youri Latortue said it could be 500,000.

President Rene Preval, for his part, told CNN that "up to now, I heard 50,000 ... 30,000" dead.

But he did not say where the estimates came from, and none of the officials were sure about the numbers. Other officials said it was too early to give an accounting of the toll.

Aid workers reported widespread destruction and suffering.

"It's the most horrific thing I've ever seen," Bob Poff, a Salvation Army worker in Port-au-Prince, told MSNBC. "We have to get food and water" quickly, he said, in describing conditions that range from stifling heat to numerous aftershocks. "We're trying to stay alive."

‘Please take me out'

Sobbing and dazed people wandered the streets of Port-au-Prince, and voices cried out from the rubble.

"Please take me out, I am dying. I have two children with me," a woman told a journalist from under a collapsed kindergarten.

The International Red Cross said some 3 million people may have been affected.

Haitian Red Cross spokesman Pericles Jean-Baptiste said his organization was overwhelmed. "There are too many people who need help ... We lack equipment, we lack body bags," he said Wednesday.

Doctors Without Borders said its three hospitals in Haiti were unusable and it was treating the injured at temporary shelters.

"The reality of what we are seeing is severe traumas, head wounds, crushed limbs, severe problems that cannot be dealt with the level of medical care we currently have available with no infrastructure really to support it," said Paul McPhun, an operations manager for the charity.

The head of the U.N. mission here was among the dead,  Preval said.

The Catholic archbishop of Port-au-Prince, Monsignor Joseph Serge Miot, was also killed.

Haiti's Radio Metropole quoted France's foreign minister, Bernard Kouchner, as saying hundreds of French nationals were missing.

According to the United Nations, the earthquake also collapsed the main prison in Haiti's capital, with reports of escaped inmates.

Radio Metropole reported that U.N. forces scrambled to protect U.N. weapons from looters ransacking the capital.

Bodies on the streets Aftershocks rattled the city as women covered in dust clawed out of debris, wailing. Stunned people wandered the streets holding hands. Thousands gathered in public squares singing hymns. People pulled bodies from collapsed homes, covering them with sheets by the side of the road. Passers-by lifted the sheets to see if a loved one was underneath. Outside a crumbled building the bodies of five children and three adults lay in a pile. The United States and other nations began organizing aid efforts, alerting search teams and gathering supplies that will be badly needed in the Western Hemisphere's poorest country. "Haiti has moved to center of the world's thoughts and the world's compassion," said British Prime Minister Gordon Brown. The United Nations said Port-au-Prince's main airport was "fully operational" and open to relief flights. Preval told the Miami Herald that he had been stepping over dead bodies and hearing the cries of those trapped under the rubble of the national Parliament building, describing the scene as "unimaginable." "Parliament has collapsed. The tax office has collapsed. Schools have collapsed. Hospitals have collapsed,'' he said. Préval issued an urgent appeal for aid. Tens of thousands of people appear to have lost their homes and many perished in collapsed buildings that were flimsy and dangerous even under normal conditions.

Video obtained by the AP showed a huge dust cloud rising over Port-au-Prince shortly after the quake as buildings collapsed.

"The hospitals cannot handle all these victims," Dr. Louis-Gerard Gilles, a former senator, said as he helped survivors. "Haiti needs to pray. We all need to pray together."

'Worse than a war zone'

Speaking from Port-au-Prince, Frank Thorp, Jr., told NBC's TODAY how he helped dig through the rubble of a building to rescue his wife. She had been trapped for 10 hours, he said.

Thorp said his spouse, who is a missionary in the country, was "doing OK" and suffered only bruises. However, a colleague who had also been buried lost both of her legs.

Thorp described conditions in Port-au-Prince as "worse than a war zone."

Even relatively wealthy neighborhoods were devastated.

People screamed for help at a wrecked hospital in Petionville, a hillside district that is home to many diplomats and wealthy Haitians as well as the poor.

At a destroyed four-story apartment building, a girl stood atop a car, trying to peer inside while several men pulled at a foot sticking from rubble. She said her family was inside.

"A school near here collapsed totally," Petionville resident Ken Michel said after surveying the damage. "We don't know if there were any children inside." He said many seemingly sturdy homes nearby were split apart.

U.N. peacekeepers were distracted from aid efforts by their own tragedy: Many spent the night hunting for survivors in the ruins of the local U.N. headquarters, where more than 100 people are missing.

A woman cries after finding the body of a loved one after the earthquake in Port-au-Prince

The quake struck at 4:53 p.m. on Tuesday, centered 10 miles west of Port-au-Prince at a depth of only 5 miles, the U.S. Geological Survey said. USGS geophysicist Kristin Marano called it the strongest earthquake since 1770 in what is now Haiti. Most of Haiti's 9 million people are desperately poor, and after years of political instability the country has no real construction standards. In November 2008, following the collapse of a school in Petionville, the mayor of Port-au-Prince estimated about 60 percent of buildings were shoddily built and unsafe in normal circumstances. Tuesday's quake was felt in the Dominican Republic, which shares the island of Hispaniola with Haiti, and in eastern Cuba, but no major damage was reported in either place. With electricity knocked out in many places and phone service erratic, it was nearly impossible for Haitian or foreign officials to get full details of the devastation within the first hours. "Everybody is just totally, totally freaked out and shaken," said Henry Bahn, a U.S. Department of Agriculture official visiting Port-au-Prince.

In Washington, State Department spokesman P.J. Crowley said that U.S. Embassy personnel were "literally in the dark" Tuesday after power failed.

Elizabeth Byrs, a spokeswoman for the U.N.'s humanitarian office, said it was working with independent aid agency Telecoms Sans Frontieres to get phone lines working again — a key element in organizing relief efforts.

Cuba said its existing field hospitals in Haiti had already treated hundreds of victims.

Venezuela's government said it would send a military plane with canned foods, medicine and drinking water and provide 50 rescue workers. Mexico, which suffered an earthquake in 1985 that killed some 10,000 people, planned to send doctors, search and rescue dogs and infrastructure damage experts.

Italy said it was sending a C-130 cargo plane Wednesday with a field hospital and emergency medical personnel as well as a team to assess aid needs. France said 65 clearing specialists, with six sniffer dogs, and two doctors and two nurses were leaving.

Edwidge Danticat, an award-winning Haitian-American author was unable to contact relatives in Haiti. She sat with family and friends at her home in Miami, looking for news on the Internet and watching TV news reports.

"You want to go there, but you just have to wait," she said. "Life is already so fragile in Haiti, and to have this on such a massive scale, it's unimaginable how the country will be able to recover from this."

NBC News, msnbc.com staff, The Associated Press and Reuters contributed to this report.