An earthquake of magnitude 6.1 rattled Indonesia's Nias island late on Saturday, sparking panic as residents fled their homes for higher ground fearing a possible tsunami, an official said on Sunday. There were no reports of casualties or damage. The Indonesian Meteorological and Geophysical Agency in Jakarta said the epicenter was about 107 km (65 miles) northwest of Nias island, which was hit by an 8.7 magnitude quake on March 28 that killed at least 600 people. Saturday's 20-km deep undersea quake struck at around midnight, leading to a power blackout for around 30 minutes. Residents in Nias's main town Gunungsitoli rushed out of their homes.