Jakarta, Sep 30 (DPA) At least 75 people were killed and hundreds were trapped under collapsed buildings after a powerful earthquake struck Indonesia's West Sumatra province Wednesday, officials said.

Vice President Jusuf Kalla said the mayor of Padang, the capital of West Samatra, told him that the quake left at least 75 people dead.

"The number may increase because many are still trapped in buildings and hotels," Kalla said.

Rustam Pakaya, the head of the Health Ministry's disaster centre, said hundreds of people were trapped under rubble in Padang, where a hospital among other structures had also collapsed.

The state-run Antara news agency reported that hundreds of people were believed to have been trapped in collapsed buildings and shops in Padang's business district and Chinatown.

A hospital official in nearby Pariaman district told TV One that eight people in the district had been killed and hundreds more hospitalized with serious injuries.

The quake, measuring 7.6 on the Richter scale, struck off the western coast of Sumatra at about 1016 GMT. A 6.2 magnitude aftershock followed about 22 minutes later.

Pakaya said a medical team was being dispatched to West Sumatra, the region worst-hit by the quake.

Telephone communications to Padang and nearby Pariaman district were cut off following the quake.

Fires also broke out in Padang, local media reported.

The National Agency for Disaster Management in the capital Jakarta said it had not been able to communicate with local officials to assess the situation.

TV One said Padang's Minangkabau airport was ordered closed until Thursday because roofs were damaged.

The Pacific Tsunami Warning Center issued an Indian Ocean tsunami alert after the quake, but later cancelled it.

The quake was also felt strongly in North Sumatra, Riau in eastern Sumatra as well as Bengkulu province in southern Sumatra, residents told Metro TV.

Indonesia, the world's largest archipelago, sits on the so-called Pacific 'Ring of Fire', the edge of a tectonic plate prone to seismic upheaval.

A major earthquake and subsequent tsunami struck in December 2004, leaving more than 170,000 people dead or missing in Indonesia's Aceh province and half a million people homeless.

Wednesday's quake occurred along the same fault line.

Geologists have said that Padang, a low-lying city of 900,000 people, risks being swallowed by a tsunami in the event of an earthquake similar in size to the one that triggered the giant waves of 2004.