Hundreds of people are still missing days after several remote Indonesian islands were hit by a deadly tsunami.
At least 343 people have died on the Mentawai Islands and almost 400 are unaccounted for, officials say, amid fears they were swept away by the wave.
Poor weather is slowing rescue efforts but an aid ship carrying food, water and medical supplies has now arrived in the disaster zone.
Indonesia's president has visited survivors on the islands.
Susilo Bambang Yudhoyono cut short a trip to Vietnam to oversee the rescue effort and headed in a helicopter loaded with food and other basic necessities to the remote and inaccessible area.
There he met local officials, promising the central government would help West Sumatra's government to build temporary homes, health facilities and schools, his spokesman said.
The islands were inundated after a 7.7-magnitude undersea earthquake triggered the tsunami three days ago.
'I know he's dead'
Aerial images from the Mentawai Islands have revealed the extent of destruction, with flattened villages plainly visible on images taken from helicopters.
Rescuers have finally reached the area where 13 villages were washed away by the 3m (10ft) wave but are still to make contact with 11 more settlements.
The scale of the damage in the worst-affected communities remains unclear.
Search teams have found bodies strewn along beaches and tossed by roadsides as they scour the islands, reports say.
However, many are still looking for their loved ones, even as the fear grows that they will not find them alive.
"I sifted through rubble, looked in collapsed houses and in the temporary shelters but there's no sign of him," Chandra, 20, told the AFP news agency as she searched for her missing baby one day after burying her husband.
"I know he's dead but I keep praying he's still alive. I'm so tired. I've not eaten for two days... I have no appetite."
Chandra and others in her community, the village of Muntei Baru Baru on North Pagai island, took the full force of the tsunami - and had little warning.
Indonesian officials have confirmed that key elements of a high-tech tsunami warning system installed in the wake of the giant Indian Ocean tsunami of 2004 were not working on Monday.
Nevertheless, the epicentre of the earthquake was so close to the Mentawai chain of islands that those living there had barely five or 10 minutes after the quake to make their escape to higher ground.
"I survived because a coconut tree fell and kept me from being swept away. My survival was a miracle from God," Chandra said.
Harmensyah, head of West Sumatra's disaster management authority told the Associated Press that rescuers were now working on the assumption that a large number of those missing would not be found alive.
"They believe many, many of the bodies were swept to sea," he said.
"Not even the foundations of houses are standing. All of them are gone. There must have been many people swept away to the Indian Ocean."
Speaking to the BBC's Indonesian service, the head of Indonesia's Red Cross said changeable weather was limiting what rescue teams could do in the disaster zone.
"The weather changes very quickly. In the morning the sea is calm but suddenly in the afternoon it rains. Our rescue workers who managed to reach the place affected still couldn't communicate with us," Hidayatul Irham said.
Problems with the early-warning system meant locals were given no indication of the coming wave.
Ridwan Jamaluddin, of the Indonesian Agency for the Assessment and Application of Technology, told the BBC's Indonesian service that two buoys off the Mentawai islands were vandalised and out of service.
"We don't say they are broken down but they were vandalised and the equipment is very expensive. It cost us five billion rupiah each (£353,000; $560,000).
However, even a functioning warning system may have been too late for people in the Mentawai Islands.
The vast Indonesian archipelago sits on the Pacific Ring of Fire, one of the world's most active areas for earthquakes and volcanoes.
More than 1,000 people were killed by an earthquake off Sumatra in September 2009.
In December 2004, a 9.1-magnitude quake off the coast of Aceh triggered a tsunami in the Indian Ocean that killed a quarter of a million people in 13 countries including Indonesia, Sri Lanka, India and Thailand.