Rescue teams headed for Indonesia's Sumatra coast on Thursday as aftershocks pounded the region where a powerful earthquake killed six people and perhaps many more the night before.
Tsunami warnings were issued but later lifted for Indian Ocean rim countries after the latest aftershocks, including a shallow quake the US Geological Survey (USGS) said had a magnitude of 7.8.
"We can expect aftershocks to continue for some time," USGS Geophysicist Dale Grant told Reuters.
The tremors sowed fresh panic among residents in Padang, the capital of West Sumatra. The town was thrown into chaos and many fled after the initial 8.4-magnitude quake, which the USGS said was the most powerful in the world this year.
"My family and neighbours are evacuating to higher ground. Everyone in the place where I live decided to evacuate," said 35-year-old Padang resident Eri Kamra.
"I saw buildings collapse and one person lost consciousness after the morning quake," he told Reuters.
Yuli Bersi, a 42-year-old, housewife said she had also fled with her three children to higher ground after the latest quakes.
"We are really scared. This is the only way for us to survive," she said. Huge traffic jams were reported in the city.
A Reuters witness said that a four-storey car showroom had collapsed, trapping several staff, and some injured people had to be moved out of hospital wards to the relative safety of tents.
Part of Padang's main hospital had also collapsed.
Officials were also deeply concerned about the situation in Bengkulu, a coastal city of about 300,000 people and the closest major town to the epicentre of last night's huge quake.
"The North Bengkulu area has been identified as the worst hit with half the area destroyed," Rustam Pakaya, head of the health ministry's crisis centre in Jakarta, said.
"Many hospitals, houses, government buildings and clinics have been destroyed," he added.
The crisis centre's latest casualty figures showed that six people had been killed and 40 injured after the first quake, which was also felt in neighbouring Singapore, Thailand and Malaysia.
"There is no explanation about why there are so many quakes hitting Indonesia at this time but Indonesia is perhaps the most active earthquake area in the world," Geophysicist Grant told Reuters.
Indonesia suffers frequent quakes, as it lies on an active seismic belt on part of the so-called Pacific "Ring of Fire".
Last Mod: 13 Eylül 2007, 10:15
A huge earthquake measuring more than 9 struck the same area of Indonesia on Dec. 26, 2004, causing a massive tsunami and over 230,000 deaths in countries across the Indian Ocean region.
Many people chose to sleep out in the open on Wednesday night rather than return indoors, said a Red Cross official in Bengkulu, a mountainous area that sees few foreign tourists.
"The emergency rescue system has mobilised and the president has ordered the military to help the rescue effort," President Susilo Bambang Yudhoyono's spokesman said.