The quake hit around 300 kilometres (190 miles) east of Bali at a depth of around 72 kilometres just off the island of Sumbawa at 6:30 am (2230 GMT Thursday), the US Geological Survey said.
"The earthquake was quite long. Most people had just woken up and they started running out from their homes. My family and I also ran away because we were afraid," Djunaedi Garib who lives in Hambala, southeast of the epicentre, on the island of Sumba told AFP.
In an initial assessment, the USGS said there was a low likelihood of casualties or damage. Indonesia's disaster agency said officials were checking to see if the quake had had any impact.
Indonesia experiences frequent seismic and volcanic activity due to its position on the Pacific "Ring of Fire", where tectonic plates collide.
