Footage shows the moments after a sports hall roof collapsed during karate practice in Padang
International rescue teams are heading to Indonesia in a last-ditch effort to free trapped earthquake survivors.
Experts from the UK, Australia and South Korea were en route to Sumatra, hit by a 7.6-magnitude quake two days ago. Others pledged emergency cash.
More than 1,000 people are already known to have died, the UN says, with thousands thought to remain trapped.
But one survivor was found on Friday: a young woman pulled, barely conscious, from within a collapsed school.
AT THE SCENE
Rachel Harvey, BBC News, Padang
Heavy diggers move across piles of rubble, slowly shifting the debris. Piledrivers are being used to break up slabs of concrete, and alongside the machinery men pick their way carefully, looking and listening for any sign of life.
They've not yet given up hope here, but the chances of finding anyone else alive must now be fading. Many hundreds of bodies are known to be trapped beneath collapsed buildings, including up to 60 children who were taking part in after school lessons when the earthquake struck.
In the grounds of the main hospital some of the injured are being treated in tents because the wards are full. One surgeon told me there was a desperate need for clean water to maintain levels of hygiene.
The rescue of Ratna Kurnia Sari was a boost to emergency workers in Padang, who were enduring tough conditions as they scrambled to reach survivors.
At least one other young woman was reported to remain trapped close to where the first rescue took place.
But as rescue efforts focused on Padang, aid workers and reporters said that in rural areas thousands more buildings had been destroyed and whole villages flattened.
"From the aerial assessments carried out yesterday, the feedback is, yes Padang city and environs are bad, but once you go outside into the surrounding rural areas, the situation is very seriously grave," said International Red Cross coordinator Christine South, quoted by AFP news agency.
There was still no information for some areas including Mentawai Island, 57km from the coast, she added.
An AP reporter said parts of Pariaman district, to the north of Padang, had virtually no buildings left standing and had received no outside help.
As many as 3,000 people were still thought to be trapped under rubble in Padang and several other areas, Indonesia's disaster management agency told the Associated Press.
Overnight, workers rigged up floodlights and brought in a giant excavator as they tried to find students trapped beneath the collapsed three-storey school.
The Jakarta Post reported that 60 children were in the school when it collapsed.
One rescue team leader, known as Suria, said hope was fading for many of those still buried.
"We have pulled out 38 children since the quake. Some of them, on the first day, were still alive, but the last few have all been dead," she told the Reuters news agency.
Part of Padang's main hospital collapsed in the quake and a makeshift open air morgue has been set up to take the growing number of yellow body bags.
Operations were being performed in nearby white tents, doctors said.
"We have done hundreds of operations since the earthquake," said Dr Nofli Ichlas.
"Some broken bones, some with limbs completely cut off. Fractured skulls, abdominal trauma too."
As the rescue efforts continued, Indonesian Health Minister Siti Fadilah Supari appealed for foreign aid to help the rescue effort.
There were calls in particular for skilled rescuers with specialised equipment to penetrate the unstable rubble.
"We need urgently electric cutters and medium-sized excavators to remove the debris," Red Cross official Febi Dwirahmadi, at the school, told AFP.
Elsewhere, teams worked at the site of the Ambacang Hotel, where as many as 100 people were thought to be trapped.
MAJOR INDONESIAN QUAKES
26 Dec 2004: Asian tsunami kills 170,000 in Indonesia alone
28 March 2005: About 1,300 killed after a magnitude 8.7 quake hits the coast of Sumatra
27 May 2006: Quake hits ancient city of Yogyakarta, killing 5,000
17 July 2006: A tsunami after a 7.7 magnitude quake in West Java province kills 550 people
30 Sept 2009: 7.6 magnitude quake near Sumatran city of Padang, thousands feared dead
1 Oct 2009: Second of two quakes near Padang, magnitude 6.8 - no damage or casualties reported
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