The death toll stood at nearly 400 people in Indonesia on Saturday as rescuers and others reacted to a devastating magnitude-7.5 earthquake and tsunami affecting the island if Sulawesi.

The nation's disaster agency counted 384 dead, all of them in the city of Palu, with the grim figure only expected to continue rising, Agence France-Presse reported.

The tsunami hit two central Indonesian cities, sweeping away buildings and pulverizing a substantial bridge, dumping victims caught in its relentless path across a devastated landscape that rescuers were struggling to reach, hindered by damaged roads and broken communications.

Four hospitals in Palu, the paralyzed capital of Central Sulawesi province, reported 48 dead and hundreds of injured but many victims were still to be accounted for, disaster agency spokesman Sutopo Purwo Nugroho told a news conference. He said the fate of "tens to hundreds" of people involved in a beach festival in Palu when the tsunami struck was unknown.

A mosque heavily damaged by the quake was half submerged and a shopping mall was reduced to a crumpled hulk.

The 10-foot-high tsunami was triggered by the earthquake and smashed into two cities and several settlements at dusk on Friday.

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.

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

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

Nugroho has said that essential aircraft can land at Palu airport's though AirNav, which oversees aircraft navigation, said 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 on Friday night said he had instructed the security minister to coordinate the government's response to a quake and tsunami that hit central Sulawesi.

Joko "Jokowi" Widodo also told reporters in his hometown of Solo that he had called on the country's military chief help with search and rescue efforts.

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

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.

The Associated Press contributed to this story.