Palu (Indonesia), Sep 30 (AFP) The death toll from a powerful earthquake and tsunami on the Indonesian island of Sulawesi has reached 420, state media said Sunday, as rescuers scrambled to reach the stricken region and survivors helped to retrieve the remains of those killed.

The official Antara agency quoted the head of the national disaster agency giving the latest toll in the coastal city of Palu, while authorities warned casualties were "increasing" as news arrived from remote areas cut off by the 7.5-magnitude earthquake and 1.5-metre (five feet) high tsunami.

At least 540 people had been badly injured, an agency spokesman said, as hospitals struggled to cope with the influx of casualties.

Indonesian president Joko Widodo said the military was being called in to the region to help search-and-rescue teams get to victims and find bodies.

Some government planes carrying relief supplies managed to land at the main airport in Palu, although officials said it would likely remain closed to commercial flights for days.

There were concerns over the whereabouts of hundreds of people preparing for a beach festival that had been due to start Friday, the disaster agency said.

In Palu - home to 350,000 people - partially covered bodies lay near the shore after waves hit the coast Friday.

Survivors sifted through a tangled mess of corrugated steel roofing, timber, rubble and flotsam up to 50 metres inland.

One man was seen carrying the muddy corpse of a small child.

Many did not return to their homes as night fell and slept in makeshift shelters, terrified that powerful aftershocks could topple damaged homes.

Hospitals were overwhelmed by the influx of those injured, with many people being treated in the open air.

The tsunami was triggered by a strong quake that brought down buildings and sent locals fleeing for higher ground as a churning wall of water crashed into Palu, where there were widespread power blackouts. "We all panicked and ran out of the house" when the quake hit, said Anser Bachmid, a 39-year-old Palu resident.

Dramatic video footage captured from the top floor of a parking ramp in Palu, nearly 80 kilometres from the quake's epicentre, showed waves bring down several buildings and inundate a large mosque.

"I just ran when I saw the waves hitting homes on the coastline," said Palu resident Rusidanto, who like many Indonesians goes by one name.

About 17,000 people had been evacuated, the disaster agency said.

"This was a terrifying double disaster," said Jan Gelfand, a Jakarta-based official at the International Federation of Red Cross and Red Crescent Societies.

"The Indonesian Red Cross is racing to help survivors but we don't know what they'll find there." The massive tremors were felt hundreds of kilometres away and there has been little word about casualties in Donggala, a region north of Palu where at least one person was reported dead in Friday's quakes.

"We have heard nothing from Donggala and this is extremely worrying," Gelfand said.

"There are more than 300,000 people living there. This is already a tragedy, but it could get much worse." Pictures supplied by the disaster agency showed a badly damaged shopping mall in Palu where at least one floor had caved in. (AFP) ABH

(This is an unedited and auto-generated story from Syndicated News feed, LatestLY Staff may not have modified or edited the content body)