Strong aftershock shakes Haiti, week after earthquake
Rescuers applaud as the children are pulled alive from the ruins
A strong aftershock has rocked Haiti, sending screaming people running into the streets, eight days after another quake devastated the country.
The extent of the damage is not yet known. The magnitude 6.1 tremor struck west of Port-au-Prince at 0603 local time (1103 GMT).
An estimated 200,000 people died in last Tuesday's quake and another 1.5 million were made homeless.
Despite an international aid operation, supplies are slow to reach survivors.
However, international teams are still rescuing people alive from the rubble, including a 69-year-old woman pulled from the ruins of a church in the capital.
The US military has defended its handling of the rescue operation, as aid groups complained of long delays in getting vital supplies of food, water and medicine.
Haitian President Rene Preval said aid delivery was the main problem now.
Help came "very fast," Mr Preval told a French radio station. "When it arrives, the question is: where are the trucks to transport it, where are the depots?"
The US Geological Survey said Wednesday's tremor was centred 35 miles (56km) north-west of the capital. It struck at a depth of 6.2 miles (9.9km), but was too far inland to generate any tsunamis in the Caribbean.
We were forced to buy a saw in the market to continue amputations
Some buildings already weakened by last week's quake collapsed and wails of terror filled the air as frightened survivors poured out of unstable buildings, a BBC correspondent in the region said.
Although some aid has started to reach desperate survivors, hundreds of thousands are still without food or water, a full week after the disaster.
Medicins Sans Frontieres (Doctors Without Borders) said its cargo plane with 12 tonnes of medical supplies had been turned away from the congested Port-au-Prince airport three times since Sunday. It said five patients died from lack of the supplies it carried.
"We were forced to buy a saw in the market to continue amputations," the group's Loris de Filippi told the Reuters news agency in Cite Soleil.
But the US military has defended its efforts in the face of vast logistical challenges.
"We're doing everything in our power to speed aid to Haiti as fast as humanly possible," said Gen Douglas Fraser, head of US Southern Command.
He said they plan to start using two other airports, at Jacmel in Haiti and San Isidro in the neighbouring Dominican Republic, in the coming days.
One full week after the magnitude seven quake devastated the country, search-and-rescue teams were emerging from the ruins with unbelievable success stories.
Ena Zizi, 69, was rescued from the wreckage of the residence of Haiti's Roman Catholic archbishop on Monday, a day before crews recovered the body of the archbishop himself, Monsignor Joseph Serge Miot.
Another survivor, 25-year-old Lozama Hotteline, was rescued from beneath a collapsed supermarket with the help of teams from Turkey and France.
Television pictures showed her smiling and singing as she was carried to safety.
The United Nations said early on Wednesday that 121 people had been rescued by international teams since the 12 January earthquake - an extra 31 people on Tuesday.
In a bid to speed up the delivery of aid and stem looting and violence, US troops have stepped up their presence in the quake-ravaged country.
AT THE SCENE
Mark Doyle, BBC News, Port-au-Prince
Haiti was extremely poor even before the earthquake, and this disaster has now broken all the basic services, like phones and electricity.
But Haitians are resilient. Everywhere there are volunteers filling some of the gaps created by the slow arrival of international aid.
A company which sells drinking water is distributing it free to people living in a school compound.
A Haitian Jesuit priest has mobilised local relief workers and international doctors to work together in a rural region just outside the capital.
In a slum area, a volunteer first-aider dressed the wounds of a girl who had been trapped in rubble.
These largely unsung heroes know they can't replace the big foreign aid agencies, but they're doing what they can to fill the gaps.
US Black Hawk helicopters swooped down on the grounds of Haiti's wrecked presidential palace on Tuesday, dropping scores of US troops who moved to secure a nearby hospital and set up aid distribution points.
US Army Maj Gen Daniel Allyn, the deputy commander for relief operations in Haiti, said the military had delivered 400,000 bottles of water and 300,000 food rations since last Tuesday's earthquake.
He said the number of US troops would grow to 10,000 in the coming weeks.
Meanwhile, the UN Security Council voted to temporarily boost its peacekeeping forces by 3,500 personnel. UN officials said they would accompany US troops as they delivered supplies.
While military escorts are still needed to deliver relief supplies, the United Nations said fears of violence and looting had eased.
"The overall security situation in Port-au-Prince remains stable, with limited, localised violence and looting occurring," the UN Office for Coordination of Humanitarian Affairs said.
So far, feared infectious diseases have not shown up, although many injured faced the immediate threats of tetanus and gangrene, and hospitals are overwhelmed.
The UN says "localised looting" is occurring, but overall security is good
The Pentagon said a navy hospital ship, the USNS Comfort, had received its first Haitian patients, even as it was still heading towards Haiti.
US Defence Secretary Robert Gates said the military is sending additional ships to help with earthquake recovery in Haiti, including one that could remove debris blocking the main port.
The World Food Programme said it was planning to bring in 10,000 gallons (40,000 litres) of diesel a day from the neighbouring Dominican Republic as Haitian fuel supplies dried up.
Haitian officials say the death toll from the quake was likely to be between 100,000 and 200,000, and that 75,000 bodies had already been buried in mass graves.
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