The Pacific Tsunami Warning Center warned of "hazardous waves" after a 7.3 magnitude earthquake struck 100 kilometers north of an Indonesian town called Maumere in the Flores Sea.
The US Geological Survey (USGS) said the powerful quake was registered at a depth of 18.5 kilometers (11 miles) in the Flores Sea at 12:20pm local time.
The Pacific Tsunami Warning Center said "hazardous waves are possible for coasts located within 1,000 km (600 miles) of the quake epicenter."
The USGS said there was a small chance of casualties from the earthquake.
But it added that "recent earthquakes in this area have caused secondary hazards such as tsunamis and landslides that might have contributed to losses."
"Everyone ran out into the street," Agustinus Florianus, a resident of Maumere town on Flores island, told Reuters news agency.
A 5.6-magnitude aftershock struck in the town of Larantuka on East Flores Island.
"We have checked and there are no reports of damage," East Flores district chief Anton Hayon told Kompas TV.