The quake struck at 05:30 a.m. local time Friday (2230 GMT Thursday).

The epicenter, with a depth of 91 km under sea bed, is located 59 km southwest of Sumba Barat Daya, an official of the agency told Xinhua by phone.

Indonesia is prone to quakes as it lies on a vulnerable quake-hit zone called "the Pacific Ring of Fire."

Earlier this month, a shallow 6.5-magnitude quake rocked Aceh province of western Indonesia, leaving 103 people dead with huge damage.