Rescue workers are hunting for survivors after a powerful earthquake hit the Indonesian island of Sulawesi and triggered a tsunami, killing at least 384 people.

After the 7.5-magnitude earthquake hit Friday, water smashed into buildings and swept away homes in the coastal city of Palu, home to 350,000 people.

More than 540 people are being treated in several local hospitals amid the massive destruction in Palu and 29 people are missing.

The death toll could climb in the coming days, Disaster Management Agency spokesman Sutopo Purwo Nugroho warned.

Electricity and communications have been cut off, making it difficult to assess the damage in Palu and nearby fishing community of Donggala, Sutopo said.

"It is not just the people in the large urban areas. There are a lot of people also living in remote communities who are hard to reach" Jan Gelfand, head of the International Red Cross in Indonesia, told CNN.

With Palu airport closed, relief workers have to make their way to Palu by road. Sulawesi is one of the biggest islands in the world and the drive from the nearest airport is around 10-12 hours. "We already have people en route but you never know what damage there is to the road infrastructure."

In Palu, authorities are still urging residents to not go inside their homes and sleep away from buildings - fields, roads or yards because of the danger from aftershocks.

BDST: 2005 HRS, SEP 29, 2018
AP