JAKARTA (AFP, REUTERS) - A powerful earthquake killed at least 42 people and injured hundreds on Indonesia’s island of Sulawesi on Friday (Jan 15), trapping several under rubble and unleashing dozens of aftershocks as authorities warned of more quakes that could trigger a tsunami.

Thousands of frightened residents fled their homes for higher ground when the magnitude 6.2-quake struck 6km north-east of the town of Majene, at a depth of just 10km, shortly before 1.30am.

The quake and aftershocks damaged more than 300 homes and two hotels, as well as flattened a hospital and the office of a regional governor, where the authorities told Reuters several people have been trapped under the rubble.

Rescuers were searching for more than a dozen patients and staff trapped beneath the rubble of the levelled Mamuju hospital.

"The hospital is flattened – it collapsed," said Arianto from the rescue agency in Mamuju city, who goes by one name.

"There are patients and hospital employees trapped under the rubble and we’re now trying to reach them," he added, without giving a specific figure.

Rescuers were also trying to reach a family of eight trapped under the rubble of their destroyed home, he added.

The country’s search-and-rescue agency said at least one hotel had partially collapsed after the quake struck at 2.18am local time on Friday (2.18am Singapore time), while the regional governor’s office also suffered extensive damage.

A resident of Mamuju, the capital of West Sulawesi, said damage across the city of some 110,000 was extensive.

"Roads are cracked and many buildings collapsed, including the governor’s office as well as the hospital. The hospital has been flattened," said 28-year-old Hendra, who goes by one name.

"The quake was very strong... I woke up and ran away with my wife."

The United States Geological Survey said the epicentre was 36km south of Mamuju and that the quake had a relatively shallow depth of 18km.

Images supplied by the search-and-rescue agency showed what appeared to be metal building frames and other debris on the ground near a local hospital.

Another showed rescue workers checking on two sisters who were trapped under rubble. It was not clear where they were trapped.

The quake was felt strongly for about seven seconds but did not trigger a tsunami warning.

Videos on social media showed residents fleeing to higher ground on motorcycles, and a child trapped under the rubble as people tried to remove debris with their bare hands.

Some buildings were badly damaged, including two hotels, the governor’s office and a mall, journalist Sudirman Samual, who is based in Mamuju, north of the epicentre, told Reuters.

At least one route into Mamuju had been cut off, he said, because of damage to a bridge.

Hours earlier on Thursday, a 5.9-magnitude earthquake struck in the same district, damaging several houses.

Indonesia’s disaster agency said a series of quakes in the past 24 hours had caused at least three landslides, and the electricity supply had been cut.

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.