Earthquake in Indonesia, Tsunami possibility
Breaking news graphic
A major quake in the Indian Ocean has hit the coast of the Indonesian tsunami-hit island of Sumatra, triggering an alert across the region.
The quake was given a magnitude of 8.2 by the US Geological Survey who have warned it could cause tidal waves.
The epicentre was located at about 200 km (125 miles) off the mainland.
The US Pacific Tsunami Warning Center said the quake could cause a "widely destructive tsunami" and it was felt as far away as Malaysia.
"Authorities in those regions should be aware of this possibility and take immediate action," the center said in a statement on its website.
It comes three months after a major earthquake and subsequent tsunami in the Indian Ocean on 26 December caused major damage and killed tens of thousands of people in the region.
Russ Evans, a seismologist from the British Geological Survey, told the BBC the Boxing Day earthquake had a magnitude of 9.5.
He says the latest quake was almost certainly an after-shock from the first one and that a tsunami was certainly possible, but on a smaller scale.
'I heard my neighbours screaming'
The quake struck between the Sumatran cities of Padang and Medan at around 2315 local time (1615 GMT) and lasted up to three minutes, said Ramlan of Indonesia's Meteorological and Geophysics Office.
Power blackouts and major panic ensued, local officials told AFP news agency.
The quake was felt across the region with people in the Malaysian capital, Kuala Lumpur, some 500km away, evacuating high-rise buildings and running out into the streets.
"I was getting ready for bed, and suddenly, the room started shaking," said Kuala Lumpur resident Jessie Chong.
"I thought I was hallucinating at first, but then I heard my neighbours screaming and running out."
Thailand, which was also hit by the 26 December disaster, has issued an tsunami alert.