At least 1,100 people have died in the earthquake that struck the Indonesian island of Sumatra on Wednesday, the UN humanitarian chief has said.
John Holmes said many hundreds more had been injured, and both figures were set to rise further.
Rescuers are working into the night to find survivors in the rubble of hundreds of collapsed buildings.
The 7.6-magnitude quake struck close to the city of Padang, the capital of West Sumatra province.
The earthquake brought down hospitals, schools and shopping malls, cut power lines and triggered landslides.
Indonesian President Susilo Bambang Yudhoyono visited some of the worst-hit areas.
"I ask rescue workers to continue working in teams with clear goals to keep looking for survivors...," he said.
"This is a natural disaster, so let us remain strong in dealing with it."
Mr Holmes told reporters: "The latest figures we have suggest the death toll has risen already to 1,100.
"Obviously [there are] many hundreds of injured people as well, and again these numbers, I fear, will rise as more information becomes available."
An assessment team is to arrive in Padang on Friday, and UN officials will decide whether to launch an emergency appeal or take money from the organisation's Central Emergency Relief Fund, Mr Holmes added.
Indonesian health officials have already predicted thousands of deaths, comparing the quake to one in the Javan city of Yogyakarta in 2006.
A second quake of 6.8 struck close to Padang at 0852 local time (0152 GMT) on Thursday but there were no immediate reports of casualties or damage.
Heavy machinery
The first earthquake struck at 1716 local time (1016 GMT) on Wednesday, some 85km (55 miles) under the sea, north-west of Padang, the US Geological Survey said.
One of the worst disasters appeared to be the collapse of a school in Padang.
One mother, Andriana, told AFP news agency she had been at the school since the first quake occurred, hoping for news of her 14-year-old daughter.
"I haven't been home yet and keep praying to God my daughter is alive."
Police said nine children had been found alive but that eight bodies had also been pulled from the rubble so far.
