PORT-AU-PRINCE, Haiti >> The largest earthquake ever recorded in the area rocked Haiti on Tuesday, collapsing a hospital where people screamed for help and damaging other buildings. An aid official described “;total disaster and chaos.”;

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

Karel Zelenka, a Catholic Relief Services representative in the capital of 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.

The earthquake had a preliminary magnitude of 7.0 and was centered about 10 miles (15 kilometers) west of Port-au-Prince, the U.S. Geological Survey said. It had a depth of 5 miles (8 kilometers). It was the largest quake recorded in the area and the first major one since a magnitude-6.7 temblor in 1984, USGS analyst Dale Grant said.

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

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 said he had not been able to get through by phone to Haiti since.

Don Blakeman, an analyst at the USGS in Golden, Colorado, said such a strong quake carried the potential for widespread damage.

“;I think we are going to see substantial damage and casualties,”; he said.

The earthquake's size and proximity to populated Port-Au-Prince likely caused widespread casualties and structural damage, added quake expert Tom Jordan at the University of Southern California.

“;It's going to be a real killer,”; he said.

The temblor appeared to have occurred along a strike-slip fault, where one side of a vertical fault slips horizontally past the other, Jordan said.

“;Whenever something like this happens, you just hope for the best,”; he said. “;The damage caused by this earthquake is not going to be pretty.”;

Minor earthquakes are common in the Caribbean, but there has not been a major one in Haiti in 16 years. The country of about 9 million people, most of them desperately poor, has struggled with political instability and 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 the buildings were shoddily built and unsafe in normal circumstances.

The quake was felt in the Dominican Republic, which shares a border with Haiti on the island of Hispaniola, and some panicked residents in the capital of Santo Domingo fled from their shaking homes. But no major damage was reported there.

In eastern Cuba, houses shook but there were also no reports of significant damage.

“;We felt it very strongly and I would say for a long time. We had time to evacuate,”; said Monsignor Dionisio Garcia, archbishop of Santiago.

Haiti, however, was another story.

“;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.”;

Bahn said he was walking to his hotel room when the ground began to shake.

“;I just held on and bounced across the wall,”; he said. “;I just hear a tremendous amount of noise and shouting and screaming in the distance.”;

Bahn said there were rocks strewn about and he saw a ravine where several homes had stood: “;It's just full of collapsed walls and rubble and barbed wire.”;

In the community of Thomassin, just outside Port-au-Prince, Alain Denis said neighbors told him the only road to the capital had been cut but that phones were all dead so it was hard to determine the extent of the damage.

“;At this point, everything is a rumor,”; he said. “;It's dark. It's nighttime.”;

Former President Bill Clinton, the U.N.'s special envoy for Haiti, issued a statement saying his office would do whatever he could to help the nation recover and rebuild.

“;My thoughts and prayers are with the people of Haiti,”; he said.

In Washington, State Department spokesman Gordon Duguid said U.S. officials were holding emergency meetings.

“;We need to gather what information we can quickly. We will of course assist in any way we can,”; he said.

Felix Augustin, Haiti's consul general in New York, said he was concerned about everyone in Haiti, including his relatives.

“;Communication is absolutely impossible,”; he said. “;I've been trying to call my ministry and I cannot get through. ... It's mind-boggling.”;

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Associated Press videographer Pierre Richard Luxama in Haiti and AP writers David Koop in Mexico City, David McFadden and Danica Coto in San Juan, Puerto Rico; Matthew Lee in Washington; Alicia Chang in Los Angeles and Andrea Rodriguez in Havana contributed to this report.