Haitians piled bodies along the devastated streets of their capital Wednesday after a powerful earthquake crushed thousands of structures, from schools and shacks to the National Palace and the U.N. peacekeeping headquarters. Untold numbers were still trapped.

It seemed clear that the death toll from Tuesday afternoon's magnitude-7.0 quake would run into the thousands. Among them was the Roman Catholic archbishop of Port-au-Prince, and France's foreign minister said the head of the U.N. peacekeeping mission also was apparently among the dead.

International Red Cross spokesman Paul Conneally said a third of Haiti's 9 million people may need emergency aid and that it would take a day or two for a clear picture of the damage to emerge. The United Nations said the capital's main airport was "fully operational" and that relief flights would begin Wednesday.

Aftershocks continued to rattle the capital of 2 million people as women covered in dust clawed out of debris, wailing. Stunned people wandered the streets holding hands. Thousands gathered in public squares to sing hymns.

People pulled bodies from collapsed homes, covering them with sheets by the side of the road. Passersby lifted the sheets to see if loved ones were underneath. Outside a crumbled building the bodies of five children and three adults lay in a pile.

The promiment died along with the poor: the body of Archbishop Joseph Serge Miot, 63, was found in the ruins of his office, said Father Pierre Le Beller of the Saint Jacques Missionary Center in Landivisiau, France. He told The Associated Press by telephone that fellow missionaries in Haiti told him they found Miot's body.

The United States and other nations _ from Iceland to Venezuela _ said they would start sending aid workers and rescue teams to Haiti the start of a major emergency operation. The international Red Cross and other aid groups announced plans for major relief operations in the Western Hemisphere's poorest country.

Many will have to help their own staff as well as stricken Haitians. Taiwan's Foreign Ministry said its embassy was destroyed and the ambassador hospitalized. Spain said its embassy was badly damaged.

"Haiti has moved to center of the world's thoughts and the world's compassion," British Prime Minister Gordon Brown said.

Tens of thousands of people lost their homes as buildings that were flimsy and dangerous even under normal conditions collapsed in the shaking. Nobody offered an estimate of the dead, but the numbers were clearly enormous.

"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."

A young American aid worker was trapped for about 10 hours under the rubble of her mission house before she was rescued by her husband, who told CBS's "The Early Show" that he drove 100 miles (160 kilometers) to Port-au-Prince to find her when he learned of the quake.

Frank Thorp said he dug for more than an hour to free his wife, Jillian, and a co-worker, from under about a foot of concrete.

Even relatively wealthy neighborhoods were devastated.

An Associated Press videographer saw a wrecked hospital where people screamed for help 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 of about 16 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.

The U.N.'s 9,000 peacekeepers in Haiti, many of whom are from Brazil, were distracted from aid efforts by their own tragedy: Many spent the night hunting for survivors in the ruins of their headquarters.

"It would appear that everyone who was in the building, including my friend Hedi Annabi, the United Nations' Secretary General's special envoy, and everyone with him and around him, are dead," French Foreign Minister Bernard Kouchner said on RTL radio.

U.N. peacekeeping chief Alain Le Roy would not confirm that Annabi was dead but said he was among more than 100 people missing in the rubble of its headquarters. He said only about 10 people had been pulled out, many of them badly injured. Fewer than five bodies had been pulled from the rubble, he said.

Brazil's army said at least four of its peacekeepers were killed and five injured, while Jordan's official news agency said three of its peacekeepers were killed and 33 injured. A state newspaper in China said eight Chinese peacekeepers were known dead and 10 were missing _ though officials later said the information was not confirmed.

Much of the National Palace pancaked on itself, but Haiti's ambassador to Mexico, Robert Manuel, said President Rene Preval and his wife survived the earthquake. He had no details.

The quake struck at 4:53 p.m., centered 10 miles (15 kilometers) west of Port-au-Prince at a depth of only 5 miles (8 kilometers), the U.S. Geological Survey said. USGS geophysicist Kristin Marano called it the strongest earthquake since 1770 in what is now Haiti.

Most Haitians 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.

"Everybody is just totally, totally freaked out and shaken," said Henry Bahn, a U.S. Department of Agriculture official visiting Port-au-Prince. "The sky is just gray with dust."

President Barack Obama offered prayers for the people of Haiti and said the U.S. stood ready to help. Rajiv Shah, administrator of the U.S. Agency for International Development, said a disaster response team would fly in Wednesday.

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."

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Associated Press videographer Pierre Richard Luxama in Port-au-Prince and AP writers David Koop and Olga R. Rodriguez in Mexico City; David McFadden and Danica Coto in San Juan, Puerto Rico; Matthew Lee in Washington; Tamara Lush in Tampa, Fla.; and Jennifer Kay and Christine Armario in Miami contributed to this report.