Damage from an earthquake and tsunami can be seen in Palu, Central Sulawesi, Indonesia. (Photo: Reuters)

|  

Dozens of people were reported to be still trapped in the rubble of a hotel 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.

With the death toll so far from Palu alone and reports only slowly filtering in from Donggal, a region of 300,000 people north of Palu and closer to the epicentre, authorities are bracing for worse to come.

Indonesia's Vice President Jusuf Kalla said the toll could rise to thousands.

Hundreds of people had gathered for a festival on the Palu's beach when the wall of water smashed onshore at dusk on September 28, sweeping many to their deaths and destroying anything in its path. Indonesian President Joko

Widodo was scheduled to visit evacuation centres in the city on September 30.

The Head of the National Disaster Management Agency (BNPB), Willem Rampangilei, told reporters in Sulawesi late on September 29 the death toll from Palu had reached 420 people, according to news website Kompas.

"It's estimated that 10,000 refugees are scattered in 50 points in Palu city," he was quoted by Kompas as saying. "We are having difficulty deploying heavy equipment to find victims under the rubble of buildings because many of the roads leading to Palu city are damaged."

Amateur footage shown by local TV stations showed waves crashing into houses along Palu's shoreline, scattering shipping containers and flooding into a mosque in the city.

Dozens of injured people were being treated in makeshift medical tents set up outdoors.

Photos confirmed by authorities showed bodies being lined up along the street on September 29, some in bags and some with their faces covered with clothes.

BNPB spokesman Sutopo Purwo Nugroho told a briefing in Jakarta the damage was "extensive" and said thousands of houses, hospitals, shopping malls and hotels had collapsed. A bridge was washed away and the main highway to Palu was cut off due to a landslide.

"The tsunami didn't come by itself, it dragged cars, logs, houses, it hit everything on land," Nugroho said, adding the tsunami had travelled across the open sea at speeds of 800 kph (500 mph) before striking the shoreline.

Metro TV reported hundreds of people had gathered outside a collapsed mall on Sunday, looking for relatives feared trapped under rubble.

Nugroho said casualties and damage could be greater along the coastline for 300 km (200 miles) north and south of Palu, including the region of Donggala.

The Red Cross said staff and volunteers were heading to the affected areas.

"We're now getting limited communications about the destruction in Palu city, but we have heard nothing from Donggala and this is extremely worrying. There are more than 300,000 people living there," Red Cross said in a statement.

"This is already a tragedy, but it could get much worse."

Donggala's waterfront and port was extensively damaged, with houses swept into the sea and bodies trapped in the rubble, according to a Metro TV reporter on the scene.

Australia’s Prime Minister Scott Morrison said Indonesia had not yet asked for help but he contacted President Joko Widodo overnight to offer support and deep sympathies.

"It is horrifying,” he told ABC TV’s Insiders programme on September 30.

"To secure the scene and make sure that issues do not deteriorate further, I think, will be a big challenge,” he said. "But I know that President Widodo will be taking a very direct and close interest in how these issues are managed and if he needs our help, he’ll have it.”

The military has started sending in cargo planes with aid from Jakarta and other cities, authorities said, but evacuees still badly needed food and other basic necessities.

Palu's airport was damaged in the quake, but was reopened for limited commercial flights on September 30, authorities said.

Indonesia sits on the Pacific Ring of Fire and is regularly hit by earthquakes, including the devastating Boxing Day 2004 earthquake and tsunami that killed more than 120,000 in northern Aceh province alone.

In August, a series of major quakes killed more than 500 people in the tourist island of Lombok and destroyed dozens of villages along its northern coast.

Palu was hit by tsunami in 1927 and 1968, according to BNPB.