PALU, Indonesia — Dozens of rescuers have been deployed to areas devastated by an earthquake and tsunami that killed hundreds of people — but damaged roads and limited communication were hampering efforts.

A wave almost 10 feet high, triggered by Friday's magnitude-7.5 earthquake, smashed into the cities of Palu and Donggala cities and several other settlements. It swept away buildings and pulverized a substantial bridge, dumping victims caught in its relentless path across a devastated landscape.

In the city of Palu at least 384 people were killed, according to Indonesian national disaster agency spokesman Sutopo Purwo Nugroho, and approximately 540 people were injured. Nearly 17,000 people in the city had been displaced and more than two dozen were considered missing.

Jan Gelfand, director of the International Federation of Red Cross and Red Crescent Societies Country Cluster Support office in Jakarta, said that he expected the death toll to rise.

"You know, I pray dearly and into my heart, I hope that doesn't happen, but as my experience tells me, as we get farther in, and more rescue is done, or more attempted rescue is done ... we're going to find that those numbers are going to go up," he said.

Nugroho said the fate of "tens to hundreds" of people involved in a beach festival in Palu when the tsunami struck was unknown.

The Indonesian Red Cross, Palang Merah Indonesia, was emptying its warehouses of emergency supplies, coordinating volunteers and distributing ambulances and heavy equipment. However, the closure of the airport near the city of Palu, and disrupted roads, meant the mission would take at least 10 hours, spokesman for the International Federation of the Red Cross, Matthew Cochrane, tweeted.

"What we've seen on the images that have come on television and on social media is what happened in the urban areas, we haven't even seen information from Donggalu really," Gelfand said. "So couple that with going deeper into the inland, and where there's smaller towns, and rural communities, they would not have escaped from this either."

Palu, which has more than 380,000 people, was strewn with debris from collapsed buildings. A mosque heavily damaged by the quake was half submerged and a shopping mall was reduced to a crumpled hulk. Bodies lay partially covered by tarpaulins and a man carried a dead child through the wreckage.

Survivors rest on trollies outside a hospital in Palu, Indonesia. ANTARA FOTO / Reuters

The city is built around a narrow bay that apparently magnified the force of the tsunami waters as they raced into the tight inlet.

In the nearby city of Donggala, home to nearly 300,000 people, a large bridge with yellow arches that spanned a coastal river had collapsed.

Indonesian TV showed a video of a powerful wave hitting Palu, with people screaming and running in fear. The water smashed into buildings and the damaged mosque.

Damage caused by a tsunami in Palu, Indonesia. AP

Communications with the area were difficult because power and telecommunications were cut, hampering search and rescue efforts.

"It's gonna take some time given the infrastructure, the communication and the remoteness to get in there and do an assessment on how badly people have been affected," Gelfand said.

Nugroho has said that essential aircraft can land at Palu airports although AirNav, which oversees aircraft navigation in the country, reported the runway is cracked and the control tower damaged.

AirNav said one of its air traffic controllers, aged 21, died in the quake after staying in the tower to ensure a flight he'd just cleared for departure got airborne safely. It did.

Indonesia's president Joko "Jokowi" Widodo said he had instructed the security minister to coordinate the government's response.

U.N. spokesman Stephane Dujarric said U.N. officials were in contact with Indonesian authorities and "stand ready to provide support as required."

Streets full of debris in Palu, on Sulawesi island, Indonesia. MUHAMMAD RIFKI / AFP - Getty Images

Indonesia is prone to earthquakes because of its location on the "Ring of Fire," an arc of volcanoes and fault lines in the Pacific Basin.

On Aug. 5, a powerful quake on the island of Lombok killed 505 people, most of whom died in collapsing buildings. Another series of strong quakes in mid-August killed at least a dozen on Lombok and neighboring Sumbawa island.

In December 2004, a massive magnitude 9.1 earthquake off Sumatra in western Indonesia triggered a tsunami that killed 230,000 people in a dozen countries.