PORT-AU-PRINCE, Haiti — Dazed survivors wandered past dead bodies in rubble-strewn streets yesterday, crying for loved ones, and rescuers desperately searched collapsed buildings as fear rose that the death toll from Haiti's devastating earthquake could reach into the tens of thousands.

The first cargo planes with food, water, medical supplies, shelter and sniffer dogs headed to the Western Hemisphere's poorest nation a day after the 7.0-magnitude quake flattened much of the capital of 2 million people.

Tuesday's earthquake brought down buildings great and small — from shacks in shantytowns to President Rene Preval's gleaming white National Palace, where a dome tilted ominously above the manicured grounds.

Hospitals, schools and the main prison collapsed. The capital's Roman Catholic archbishop was killed when his office and the main cathedral fell. The head of the U.N. peacekeeping mission was missing in the ruins of the organization's multistory headquarters.

Police officers turned their pickup trucks into ambulances to carry the injured. Wisnel Occilus, a 24-year-old student, was wedged between two other survivors in a truck bed headed to a police station. He was in an English class when the earth shook at 4:53 p.m. and the building collapsed.

"The professor is dead. Some of the students are dead, too," said Occilus, who suspected he had several broken bones. "Everything hurts."

Other survivors carried injured to hospitals in wheelbarrows and on stretchers fashioned from doors.

In Petionville, next to the capital, people used sledgehammers and their bare hands to dig through a collapsed shopping center, tossing aside mattresses and office supplies. More than a dozen cars were entombed, including a U.N. truck.

At a triage center in a hotel parking lot, people with cuts, broken bones and crushed ribs moaned under tent-like covers fashioned from bloody sheets.

"I can't take it anymore. My back hurts too much," said Alex Georges, 28, who was still waiting for treatment a day after his school collapsed and killed 11 classmates.

"This is much worse than a hurricane," said doctors' assistant Jimitre Coquillon. "There's no water. There's nothing. Thirsty people are going to die."

If there were any organized efforts to distribute food or water, they were not visible.

Along the city's roadsides, the true cost of Tuesday's earthquake was readily visible: the bodies of victims neatly lined up, some covered in white sheets and some not, the Los Angeles Times reported. The corpses included that of a girl, perhaps a teenager, in pink shorts; a couple lying next to one another; a man covered in a sheet, save for his horribly swollen feet poking out from beneath.

On Martin Luther King Avenue, just past a sign that said, "Welcome to Port-au-Prince," the slender legs of three young children poked out from under their sheets, the Times reported. Three adults were next to them.

Haiti's leaders struggled to comprehend the extent of the catastrophe — the worst earthquake to hit the country in 200 years — even as aftershocks reverberated.

"It's incredible," Preval told CNN. "A lot of houses destroyed, hospitals, schools, personal homes. A lot of people in the street dead. I'm still looking to understand the magnitude of the event and how to manage."

Preval described the destruction as "unimaginable," the Times reported, and said thousands of people were probably killed. Leading Sen. Youri Latortue told The Associated Press that 500,000 could be dead, but conceded that nobody really knows.

"Let's say that it's too early to give a number," Preval said.

BODIES IN THE STREET

As dusk fell, thousands of people gathered on blankets outside the crumpled presidential palace, including hundreds of women who waved their hands and sang hymns in a joyful, even defiant tone.

Ricardo Dervil, 29, said he decided to join the crowd because he was worried about aftershocks and was tired of seeing dead bodies.

"I was listening to the radio and they were saying to stay away from buildings," he said. "All I was doing was walking the street and seeing dead people."

Balancing suitcases and belongings on their heads, people streamed on foot into the Haitian countryside, where wooden and cinderblock shacks showed little sign of damage. Ambulances and U.N. trucks raced in the opposite direction, toward Port-au-Prince.

About 3,000 police and international peacekeepers cleared debris, directed traffic and maintained security in the capital. But law enforcement was stretched thin.

Looting began immediately after the quake, with people seen carrying food from collapsed buildings.

Port-au-Prince's ruined buildings fell on both the poor and the prominent: The body of Archbishop Joseph Serge Miot, 63, was found in the ruins of his office, according to the Rev. Pierre Le Beller at Miot's order, the Saint Jacques Missionary Center in Landivisiau, France.

The United Nations said 16 U.N. personnel were confirmed dead and between 100 and 150 U.N. workers were still missing, including U.N. mission head Hedi Annabi of Tunisia and his chief deputy.

Senate President Kelly Bastien was rescued from the collapsed Parliament building and taken to a hospital in the neighboring Dominican Republic.

Even the main prison in the capital fell down, "and there are reports of escaped inmates," U.N. humanitarian spokeswoman Elisabeth Byrs said in Geneva.

BESET BY TRAGEDY

Haiti seems especially prone to catastrophe — from natural disasters like hurricanes, storms, floods and mudslides to crushing poverty, unstable governments, poor building standards and low literacy rates.

The survivors likely will face an increased risk of dengue fever, malaria and measles — problems that plagued the impoverished country before, said Kimberley Shoaf, associate director of the UCLA Center for Public Health and Disasters.

Some of the biggest immediate health threats include respiratory disease from inhaling dust from collapsed buildings and diarrhea from drinking contaminated water.

The international Red Cross said a third of the country's 9 million people may need emergency aid, a burden that would test any nation and a crushing catastrophe for impoverished Haiti.