Banda Aceh, Indonesia - A 6.6-magnitude earthquake hit off the west coast of Indonesia's Sumatra island on Wednesday, seismologists said, sending sending terrified residents fleeing from homes and buildings.

The earthquake struck at around 7.30am (00h30 GMT) 300km south-west of Medan, the capital of North Sumatra province, at a depth of 45km, the US Geological Survey said.

There were no immediate reports of damage or casualties, but a resident on Simeulue, a small island about 150km off Sumatra's west coast, said the ground shook violently for about a minute.

“People rushed out of their homes in panic. We felt strong shaking for about a minute, but so far there is no apparent sign of damage,” said Abdul Karim, a 44-year-old civil servant in Sinabang, the capital of Simeulue island.

Indonesia's meteorology agency did not issue a tsunami warning and confirmed there were no reports of casualties or damage so far.

The Australian Bureau of Meteorology also said the Indonesian earthquake posed no tsunami threat to Australia.

Indonesia sits on the Pacific “Ring of Fire” where continental plates collide, causing frequent seismic and volcanic activity. - Sapa-AFP