Thousands may have died in an earthquake that struck the city of Padang on Indonesia's Sumatra island, a minister said on Thursday, with officials saying many victims remained buried under toppled buildings.   

The 7.6 magnitude quake hit Padang on Wednesday afternoon, knocking over hundreds of buildings, but with communications patchy it was hard to determine the extent of the destruction and loss of life.

Heavy rain was also hampering rescue efforts and officials said power had been severed in the city. Television footage showed people being pulled from the rubble.

 A second magnitude 6.8 quake hit another part of Sumatra on Thursday, causing fresh panic, according to television reports.
The second quake's epicentre -- inland and further to the southeast -- was 154 km northwest of Bengkulu, the U.S.
Geological Survey said.
   

The area could not immediately be contacted.
    Health Minister Siti Fadillah Supari told reporters at an airport in Jakarta before leaving for the stricken area that the number of victims "could be more (than hundreds or thousands). I think it's more than thousands, if we look at how widespread the damage is ... but we don't really know yet."    

The national disaster agency earlier put the toll at between 100 and 200 in the city of 900,000. About 500 houses had collapsed, officials in the area said.
   

Australian businesswoman Jane Liddon told Australian radio from Padang said the city centre was devastated.
   

"The big buildings are down. The concrete buildings are all down, the hospitals, the main markets, down and burned. A lot of people died in there. A lot of places are burning.
   

"Most of the damage is in the town centre in the big buildings. The little houses, the people's houses, there are a few damaged, but nothing dramatic."    

TV footage showed piles of debris, collapsed houses and multi-storey buildings, with scores of crushed cars, after the earthquake, which caused widespread panic.

The main hospital had collapsed, roads were cut off by landslides and Metro Television said the roof of Padang airport had caved in.

The disaster is the latest in a spate of natural and man-made calamities to hit Indonesia, a sprawling archipelago of 226 million people.

Welfare Minister Aburizal Bakrie said on Wednesday damage could be similar to that caused by a 2006 quake in the central Java city of Yogyakarta that killed 5,000 people and damaged 150,000 homes.

"Hundreds of houses have been damaged along the road. There are some fires, bridges are cut and there is extreme panic here," said a Reuters witness in the city. Broken water pipes had triggered flooding, he said before his mobile phone was cut off.

The quake was felt around the region. High-rise buildings in Singapore, 440 km (275 miles) to the northeast, evacuated staff. Office buildings also shook in Malaysia's capital, Kuala Lumpur.
   

Sumatra is home to some of the country's largest oil fields as well as its oldest liquefied natural gas terminal, although there were no immediate reports of damage. Padang, capital of Indonesia's West Sumatra province, sits on one of the world's most active fault lines along the "Ring of Fire" where the Indo-Australia plate grinds against the Eurasia plate to create regular tremors and sometimes quakes.

Geologists have long warned Padang may one day be destroyed by a huge earthquake because of its location.

A 9.15 magnitude quake, its epicentre 600 km northwest of Padang, caused the 2004 tsunami that killed 230,000 people around in Indonesia and other countries across the Indian Ocean.

The depth of Wednesday's earthquake was 85 km (53 miles), the United States Geological Survey said