A powerful earthquake of magnitude 7.9 struck off the coast of Indonesia on Wednesday, southwest of the Sumatra island, according to the United States Geological Survey. The quake occurred at a depth of 10 km, 808 km southwest of Padang, the capital of West Sumatra province. The USGS initially put the magnitude at 8.2, before lowering it to 8.1 and then to 7.9.

A tsunami warning has been issued in the regions of West Sumatra, North Sumatra and Aceh, although there were no immediate reports of casualties or damage, Reuters reported. However, the shallower an earthquake, the more likely it is to cause damage. Heronimus Guru, the deputy head of operations of Indonesia's search and rescue agency, said they did not have any information about deaths so far. He had told Reuters earlier that an unconfirmed number of people had been killed in the earthquake.

Indonesia sits on the Pacific "Ring of Fire", where continental plates meet and cause strong seismic activity. The region is frequently hit by earthquakes.