Torrential monsoon rains hampered the hunt yesterday for anyone still buried alive under buildings flattened by a powerful earthquake on Indonesia's Sulawesi island, after the huge tremor killed at least 81 and left thousands homeless. 

Excavators and cranes were deployed across the devastated seaside city of Mamuju, where buildings were reduced to a tangled mass of twisted metal and chunks of concrete, including a hospital and the regional governor's office.

It was unclear how many people -- dead or alive -- could still be under mountains of debris in the aftermath of Friday's 6.2-magnitude quake.

"The rain poses risks because damaged buildings could collapse if it gets too heavy...and aftershocks could move them too," said rescuer Octavianto.

Excavating debris too fast with heavy equipment could crush and kill any buried survivors, he added.

"All the victims we've found so far were dead," said Octavianto, 37, who like many Indonesians goes by one name.

"It is most likely any more victims are already dead if 24 hours has passed," he added.

Scores of rescuers combed through the destruction, filling body bags with corpses, while police on yesterday deployed a K-9 unit of sniffer dogs to help in the search at a badly damaged hospital.

Most victims were found in Mamuju, but some were also recovered south of the city of 110,000 people in West Sulawesi province.

Friday's tremor triggered panic among residents of the island, which was hit by a 2018 quake-tsunami disaster that killed thousands.

Authorities have not given a figure for how many survivors have been rescued. A pair of young sisters plucked from under the mass of concrete and other debris were treated in hospital.

Thousands left homeless by the quake took to makeshift shelters -- many little more than tarpaulin-covered tents filled with whole families.

They said they were running low on food, blankets and other aid, as emergency supplies were rushed to the hard-hit region.

Many survivors were unable to return to their destroyed homes, or were too scared to go back, fearing a tsunami sparked by aftershocks, common after strong earthquakes.