PORT-AU-PRINCE, Haiti — A powerful earthquake struck Haiti’s capital on Tuesday with withering force, toppling everything from simple shacks to the ornate National Palace. The dead and injured lay in the streets even as strong aftershocks rippled through the impoverished Caribbean country.

Associated Press journalists based in Port-au-Prince said the damage from the quake — the most powerful to hit Haiti in more than 200 years — is staggering even in a country accustomed to tragedy and disaster. Thousands of people gathered in public squares late into the night, singing hymns and weeping.

Many gravely injured people sat in the streets early today, pleading for doctors. With almost no emergency services to speak of, the survivors had few other options.

The scope of the disaster remained unclear early today, and even a rough estimate of the number of casualties was impossible. But it was clear from a tour of the capital that tens of thousands of people had lost their homes and that many had perished. Many buildings in Haiti are flimsy and dangerous even under normal conditions.

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

An Associated Press videographer saw a wrecked hospital where people screamed for help in Petionville, a hillside Port-au-Prince district that is home to many diplomats and wealthy Haitians as well as many poor people.

Despite the destruction, the capital was largely peaceful.

The magnitude 7.0 quake struck at 4:53 p.m. Tuesday, leaving large numbers of people unaccounted for, including many of the United Nations personnel who have been keeping the peace in the country since a 2004 rebellion ousted the president.

President Rene Preval and his wife survived the earthquake, according to Robert Manuel, Haiti’s ambassador to Mexico. He said he had no other details.

Karel Zelenka, a Catholic Relief Services representative in Port-au-Prince, told U.S. colleagues before phone service failed that “there must be thousands of people dead,” according to a spokeswoman for the aid group, Sara Fajardo.

“He reported that it was just total disaster and chaos, that there were clouds of dust surrounding Port-au-Prince,” Fajardo said from the group’s offices in Maryland.

State Department spokesman P.J. Crowley said in Washington that U.S. Embassy personnel were “literally in the dark” after power failed.

“They reported structures down. They reported a lot of walls down. They did see a number of bodies in the street and on the sidewalk that had been hit by debris. So clearly, there’s going to be serious loss of life in this,” he said.

U.N. headquarters in Haiti damaged

The headquarters of the 9,000-member Haiti peacekeeping mission and other U.N. installations were seriously damaged, according to Alain Le Roy, the U.N. peacekeeping chief in New York. “Contacts with the U.N. on the ground have been severely hampered,” Le Roy said in a statement, adding: “For the moment, a large number of personnel remain unaccounted for.”

— The Associated Press