PORT-AU-PRINCE, Haiti - A powerful aftershock sent Haitians screaming into the streets on Wednesday, collapsing buildings, cracking roads and adding to the trauma of a nation stunned by an apocalyptic quake eight days ago.
The magnitude-5.9 jolt matched the strongest of the aftershocks that have followed the huge quake of Jan. 12 that devastated Haiti's capital.
The new temblor collapsed seven buildings in Petit-Goave, the seaside town closest to the epicenter, according to Mike Morton of the U.N. Disaster Assessment and Coordination agency, but there were no reports of people crushed or trapped, perhaps because the earlier quake frightened most people into sleeping outside.
Wails of terror erupted in Port-au-Prince, where the aftershock briefly interrupted rescue efforts amid the broken concrete of collapsed buildings, and prompted doctors and patients to flee the University Hospital.
Hundreds of thousands of Haitians remain homeless, hungry and in mourning _ most still waiting for the benefits of a nearly $1 billion global aid campaign.
At least one woman died of a heart attack in Port-au-Prince, according to Eddy Thomas, a private undertaker.
"She had a heart condition, and the new quake finished her," he said while pushing her body along the street on a mobile stretcher.
At a golf course where 25,000 people live under sheets of plastic and old cloth, U.S. troops and quake victims alike raced for open ground as the quake began with a slow vibration and then intensified into side-to-side shaking that lasted about eight seconds. Some in Port-au-Prince said the far stronger Jan. 12 quake seemed to last for 30 seconds.
"It kind of felt like standing on a board on top of a ball," said U.S. Army Staff Sgt. Steven Payne. The 27-year-old from Jolo, West Virginia was preparing to hand out food to some of the 25,000 refugees living under plastic and old sheets on the grounds of a nine-hole golf course.
The U.S. Geological Survey said the aftershock was centered about 35 miles (60 kilometers) west-southwest of Port-au-Prince and 6.2 miles (10 kilometers) below the surface.
It was a little further from the capital than last week's magnitude-7.0 quake, which the killed an estimated 200,000 people, left 250,000 injured and made 1.5 million homeless, according to the European Union.
The strong aftershock prompted Anold Fleurigene, 28, to grab his wife and three children and head to the city bus station. His house was destroyed in the first quake and his sister and brother killed.
"I've seen the situation here, and I want to get out," he said.
The aftershock also ripped 8-inch (20-centimeter) cracks in a road west of the capital near Leogane, where U.S. Marines were setting up a post to aid quake victims who are sleeping in streets, culverts and driveways, often under tree branches draped with sheets to guard against the sun.
The new shake, combined with a light rain on Tuesday, has complicated rescue efforts, said Dr. Yi Ting Tsai, part of a Taiwanese crew digging for survivors near the ruined cathedra.
"The problem is the rain and the new quake this morning has made the debris more compact," he said.
Wednesday's temblor matched the strongest of 49 aftershocks of magnitude-4.5 or greater that have followed the Jan. 12 quake.
USGS geophysicist Bruce Pressgrave said nobody knows if a still-stronger aftershock is possible.
"Aftershocks sometimes die out very quickly," he said. "In other cases they can go on for weeks, or if we're really unlucky it could go on for months" as the earth adjusts to the new stresses caused by the initial quake.
More aid was arriving on Wednesday, notably the U.S. Navy's floating hospital, USNS Comfort, which was already treating two severely injured quake victims when it dropped anchor in view of Port-au-Prince. She ship carries about 550 medical staff and about 60 civilian mariners.
Search-and-rescue teams have emerged from the city's ruins with some improbable success stories _ including the rescue of 69-year-old ardent Roman Catholic who said she prayed constantly during her week under the rubble.
Ena Zizi had been at a church meeting at the residence of Haiti's Roman Catholic archbishop when the Jan. 12 quake struck, trapping her in debris. On Tuesday, she was rescued by a Mexican disaster team.
Zizi said after the quake, she spoke back and forth with a vicar who also was trapped. But he fell silent after a few days, and she spent the rest of the time praying and waiting.
"I talked only to my boss, God," she said. "I didn't need any more humans."
Doctors who examined Zizi on Tuesday said she was dehydrated and had a dislocated hip and a broken leg.
Elsewhere in the capital, two women were pulled from a destroyed university building. And near midnight Tuesday, a smiling and singing 26-year-old Lozama Hotteline was carried to safety from a collapsed store in the Petionville neighborhood by the French aid group Rescuers Without Borders.
Dr. Jon Kim Andrus, deputy director for the Pan American Health Organization, said that international aid teams have saved 121 people from the rubble, "and countless more have been rescued by Haitians working with no equipment at all," he said.
The World Food Program said more than 250,000 ready-to-eat food rations had been distributed in Haiti by Tuesday, reaching only a fraction of the 3 million people thought to be in desperate need.
The WFP said it needs to deliver 100 million ready-to-eat rations in the next 30 days, but it only had 16 million meals in the pipeline.
U.S. troops landed in Seahawk helicopters Tuesday on the manicured lawn of the ruined National Palace on Tuesday, but the colossal efforts to help Haiti were proving inadequate because of the scale of the disaster. Expectations exceeded what money, will and military might have been able to achieve.
Governments have pledged nearly $1 billion in aid, and thousands of tons of food and medical supplies have been shipped. But much remains trapped in warehouses, or diverted to the neighboring Dominican Republic. Port-au-Prince's nonfunctioning seaport and many impassable roads complicate efforts to get aid to the people.
Aid is still being turned back from the single-runway airport, where the U.S. military has been criticized by some of poorly prioritizing flights. The U.S. Air Force said it had raised the facility's daily capacity from 30 flights before the quake to 180.
About 2,200 U.S. Marines have established a beachhead west of Port-au-Prince, joining 9,000 Army soldiers already on the ground. Lt. Cmdr. Walter Matthews, a U.S. military spokesman, said helicopters were ferrying aid from the airport into Port-au-Prince and the nearby town of Jacmel as fast as they could.
U.S. Defense Secretary Robert Gates said the military will send a port-clearing ship with cranes aboard to Port-au-Prince to remove debris that is preventing many larger aid ships from docking.