The epicenter of the quake, which struck at 1:28 a.m. Jakarta time, was 6 kilometers (3.7 miles) northeast of the city of Majene, at a depth of 10 kilometers (6.2 miles), according to Indonesia’s Meteorology, Climatology and Geophysics Agency.
Thirty-four people died in the city of Mamuju, to the north of the epicenter, while another eight died in Majene.
In Majene, at least 637 were injured and 15,000 residents have been displaced, according to the country’s National Board for Disaster Management (BNPB).
Thousands of residents fled their homes to seek safety following the quake, which could be felt strongly for five to seven seconds and damaged at least 300 houses in Majene, BNPB said.
Other buildings have also been badly damaged, including a military command office in Majene, and hotels and government buildings in Mamuju.
Many people are still trapped under collapsed buildings, according to local search and rescue teams.
“Our priority is saving victims who are still buried under the buildings,” Safaruddin Sanusi, head of West Sulawesi’s Communications and Information Department, told CNN Friday. “For example in the [West Sulawesi governor’s office] we are still trying to evacuate two security guards who are trapped inside.”
Nearly half of the buildings in Mamuju have been wiped out by the quake, he added.
“Most…of [the] people in Mamuju city are now displaced. They are afraid to stay at their houses.”
The communications chief also said the quake had damaged four of Mamuju’s largest hospitals.
“Mitra Manakara [Hospital] is flattened by this earthquake, while three others, Mamuju Central Hospital, Bhayangkara Hospital and Regional Hospital are also in [a] bad situation,” he said.
“We need more extrication equipment and more personnel to work fast [on] saving victims trapped under the building.”
“Our obstacle here is that we don’t have heavy equipment to rescue them,” Saidar Rahmanjaya, head of the Local Search and Rescue Agency of Mamuju, West Sulawesi, told local television.
Arianto Ardi, the section head of Mamuju’s Search and Rescue Agency, told CNN that officials had finished evacuations at three homes that were wiped out from the earthquake.
The agency evacuated eight people from the first home. Three survived and five people died.
Another difficulty was the lack of communication among rescue teams, as local telephone networks were down following the quake, he said, adding that there were eight locations where people were in urgent need of rescue.
Shalahuddin Salman, a resident of Mamuju, said many people were trapped because they were sleeping when the quake struck in the middle of the night.
“We saved four family members but one still can’t be evacuated,” he told CNN after he and a few others rescued a family from underneath a collapsed building. “(He’s) trapped inside the building. We believe he is dead.”
Shalahuddin said he worried that many people were trapped under the debris of the Mitra Manakara private hospital, an eight-floor structure that had been flattened by the quake.
Meanwhile, thousands of people who were able to flee have chosen to stay away from their homes out of fear of another earthquake or tsunami, said West Sulawesi’s Police Grand Commissioner Syamsu Ridwan.
“Some of them are going to the higher place to avoid tsunami, although we have a confirmation that we have no tsunami after this big earthquake,” he said.
The country’s Meteorology, Climatology and Geophysics Agency said the earthquake did not trigger a tsunami based on meteorology and climatology agency modeling.
The earthquake also triggered a power outage and caused three landslides along the main road connecting Majene and Mamuju.
Hours earlier on Thursday, a 5.9-magnitude earthquake struck in the same district damaging several houses.
Straddling the so-called Pacific “Ring of Fire,” Indonesia, a nation of high tectonic activity, is regularly hit by earthquakes.
In 2018, a devastating 6.2-magnitude quake and subsequent tsunami struck the city of Palu, in Sulawesi, killing thousands of people.
Correction: An earlier version of this story misstated the number of people killed in the earthquake. It is 42, according to official figures early Saturday.
Additional reporting by Reuters.