A shallow, 6.6-magnitude earthquake hit inland on the central Indonesian island of Sulawesi Monday, US seismologists said, causing people to panic but there were no immediate reports of casualties or damage.
The quake hit at a depth of nine kilometres (six miles) at 10:35 pm (1435 GMT), west of the town of Poso, according to the United States Geological Survey.
Muhammad Guntur, who lives on the outskirts of the town, said it was felt strongly.
"People are panicking here. We are now all gathered outside of our houses," he told AFP immediately after the impact.
A hotel worker in Poso also said that people panicked when the quake struck but that things had returned to normal there.
"The electricity was off for a while," said the worker Buhory, who like many Indonesians goes by one name. "People were panicking but now it is on again and everything is okay."
National disaster agency spokesman Sutopo Purwo Nugroho said the quake was felt in Poso for about 20 seconds but there had been no reports so far of casualties or damage.
Local disaster agency officials were still assessing the impact, he added.
Indonesia sits on the Pacific "Ring of Fire" where tectonic plates collide, causing frequent seismic and volcanic activity.
An earthquake struck Indonesia's western Aceh province in December, killing more than 100 people, injuring many more and leaving tens of thousands homeless.
The quake hit in one of the areas worst affected by the devastating Indian Ocean tsunami in 2004.