Rescue teams in Indonesia struggled on Sunday to reach communities feared devastated by a major earthquake and tsunami on Sulawesi island, with a toll of more than 400 killed expected to rise sharply as contact is restored with remote areas.
Dozens of people were reported to be trapped in the rubble of two hotels and a mall in the city of Palu, which was hit by waves as high as six metres (20 feet) following the 7.5 magnitude earthquake on Friday.
A young woman was pulled alive from the rubble of the Roa Roa Hotel, the news website Detik.com reported. Hotel owner Ko Jefry told Metro TV on Saturday that up to 60 people were believed trapped. Hundreds of people gathered at the mall searching for loved ones.
"We've got information from people that their relatives are still inside, so we're focusing on that, especially to find survivors," a rescuer identified as Yusuf, working at the ruins of the mall, told Metro TV.
With confirmed deaths only from Palu, authorities are bracing for much worse as reports filter in from outlying areas, in particular, Donggala, a region of 300,000 people north of Palu and closer to the epicentre of the quake.
Vice President Jusuf Kalla said the toll could rise into the thousands.
A disaster official said the tsunami travelled across the sea at speeds of 800 kph (500 mph) before striking the shore and casualties could have been caused along a 300 km (200 miles) stretch of coast, north and south of Palu.
Donggala town has been extensively damaged, with houses swept into the sea and bodies trapped in debris, according to a Metro TV reporter on the scene.
The Red Cross said it had heard nothing from the Donggala region.
"This is extremely worrying," it said in a statement.
"This is already a tragedy, but it could get much worse."
National search and rescue agency chief Muhammad Syaugi told Reuters rescuers were flying to Donggala by helicopter.
Questions about warning
Indonesia is all too familiar with deadly earthquakes and tsunamis. In 2004, a quake off Sumatra island triggered a tsunami across the Indian Ocean, killing 226,000 people in 13 countries, including more than 120,000 in Indonesia.
Questions are sure to be asked why warning systems set up around the country after that disaster appear to have failed on Friday.
The meteorological and geophysics agency BMKG issued a tsunami warning after the Friday quake but lifted it 34 minutes later, drawing criticism it had withdrawn it too quickly. But officials said they estimated the waves had hit while the warning was in force.
Hundreds of people had gathered for a festival on Palu's beach when the water smashed onshore at dusk.
Palu is at the head of a narrow bay, about 10 km long and 2 km wide, which had "amplified" the force of the wave as it was funnelled toward the city, a geophysics agency official said.
Questions have been raised about what caused the tsunami, with speculation an underwater landslide was to blame.
The BMKG said its closest sensor, about 200 km (125 miles) from Palu, had only recorded an "insignificant", six-cm (2.5 inches) wave, while researchers said it was surprising the quake, which was recorded as a "strike-slip" event, when tectonic plates move horizontally against each other rather than vertically, had generated a tsunami.
"It may be that the shock of the quake triggered a landslide underwater, but we don't have any proof yet," Abdul Muhari, who heads a tsunami research team that advises the government, told Reuters.
Video footage on social media showed a man on the upper floor of a building shouting warnings of the approaching tsunami to people on the street below moments before the wave crashed ashore. Reuters was not able to authenticate the footage.
The Head of the National Disaster Management Agency, Willem Rampangilei, told reporters in Sulawesi late on Saturday rescuers were struggling in their hunt for more victims.
"We are having difficulty deploying heavy equipment ... because many of the roads leading to Palu city are damaged," he was quoted by the Kompas newspaper as saying.
About 10,000 displaced people were scattered at 50 different places in Palu, he said.
Dozens of injured people were being treated in tents set up in the open.
'Horrifying'
Photos confirmed by authorities showed bodies lined up on a street on Saturday, some in bags and some with their faces covered by clothes.
President Joko Widodo was scheduled to visit evacuation centres on Sunday.
Australian Prime Minister Scott Morrison said Indonesia had not asked for help but he had contacted President Widodo overnight to offer support and deep sympathies.
"It is horrifying ... If he needs our help, he'll have it," he told ABC TV's Insiders programme.
The military has started sending in aircraft with aid from Jakarta and other cities, authorities said.
Palu's airport was damaged in the quake, but had reopened for limited commercial flights, authorities said.
Indonesia sits on the Pacific Ring of Fire and is regularly hit by earthquakes.
In August, a series of quakes killed more than 500 people on the tourist island of Lombok, hundreds of kilometres southwest of Sulawesi.
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