PORT-AU-PRINCE, Haiti — The capital largely has been destroyed in the most powerful earthquake to hit the country in about 240 years.

Associated Press journalists described severe and widespread casualties after a tour of streets where blood and bodies could be seen.

The damage is staggering even in a country accustomed to tragedy and disaster. AP reporters say the National Palace is a crumbled ruin, and tens of thousands of people are homeless.

Many gravely injured people were sitting in the street, pleading for doctors, hours after the quake. In public squares, thousands of people were singing hymns and holding hands.

The 7.0-magnitude quake struck at 4:53 p.m. Tuesday, leaving large numbers of people missing.

Communications were widely disrupted, making it impossible to get a full picture of damage as powerful aftershocks shook a desperately poor nation where many buildings are flimsy. Electricity was out in some places.

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 spokeswoman 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.

“Serious loss of life”

State Department spokesman P.J. Crowley said in Washington that embassy personnel “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.”

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

The U.N. peacekeeping mission’s headquarters fell and a large number of U.N. workers were missing, the peacekeeping chief said late Tuesday.

Alain Le Roy told reporters that U.N. troops, mostly from Brazil, were surrounding the wreckage of the five-story building trying to rescue people, but “as we speak no one has been rescued from this main headquarters.”

Elsewhere in the capital, a U.S. government official reported seeing houses that had tumbled into a ravine.

Denver resident Karen Ashmore is executive director of the Lambi Fund of Haiti, a nonprofit that helps Haitians with sustainable development projects. She said her group had real difficulty reaching Haiti on Tuesday.

“The only things that have been reliable has been Twitter and Facebook, the social-networking sites,” she said. “A few of our board members have satellite phones, but there aren’t that many satellite phones in Haiti.

An estimated 200 Haitians live in the metro Denver area, she said.

“We’re not first-responders like the Red Cross. We’re not aid people. We’re second-responders. We help people rebuild. And there’s going to be plenty of that,” she said.

Person wishing to donate may contact her at lambifund.org.

Kenson Calixte of Boston spoke to an uncle and a cousin in Port-au- Prince by phone shortly after the quake. He could hear screaming in the background as his relatives described a frantic scene in the streets. His uncle said a small hotel near their home had collapsed with people inside.

“They told me it was total chaos, a lot of devastation,” Calixte said.

Envoy loses contact

Haiti’s ambassador to the U.S., Raymond Joseph, said from his Washington office that he spoke to President Rene Preval’s chief of staff, Fritz Longchamp, just after the quake hit. He said Longchamp told him that “buildings were crumbling right and left” near the national palace. He had not been able to get through by phone to Haiti since.

The earthquake had a preliminary magnitude of 7.0 and was centered about 10 miles west of Port-au-Prince at a depth of 5 miles, the U.S. Geological Survey said. USGS geophysicist Kristin Marano called it the strongest earthquake since 1770 in what is now Haiti. In 1946, a magnitude-8.1 quake struck the Dominican Republic and also shook Haiti, producing a tsunami that killed 1,790 people.

Most of Haiti’s 9 million people are desperately poor, and after years of political instability, the nation has no real construction standards. In November 2008, following the collapse of a school in Petionville, the mayor of Port-au- Prince estimated that 60 percent of the buildings were shoddily built and unsafe in normal circumstances.

President Barack Obama ordered U.S. officials to start preparing humanitarian assistance. The Office of Foreign Disaster Assistance will be assembling a team to send to Haiti, Crowley said, including search-and-rescue experts.

“Communication is absolutely impossible,” said Felix Augustin, Haiti’s consul general in New York. “I’ve been trying to call my ministry, and I cannot get through. . . . It’s mind-boggling.”

Denver Post staff writer Mike McPhee contributed to this report.

Hotline for family

The State Department has set up a hotline for Americans seeking information about family members in Haiti. The toll-free number is 888-407-4747. Some callers may receive a recording because of heavy call volume. Meanwhile, aid agencies, including the Red Cross, are mobilizing to move aid and rescuers to Haiti as quickly as possible. The Associated Press