An earthquake with a preliminary magnitude of 6.1 hit Shimane Prefecture early Monday, injuring five people. Authorities warned of the possibility of another powerful temblor within the next week or so.

According to the Meteorological Agency, the quake, which also caused a blackout and disrupted water supplies, occurred at 1:32 a.m. at a depth of 12 km. It registered upper 5 on the Japanese seismic intensity scale of 7.

Four people were injured in the city of Oda, including a 17-year-old boy who fell from his bed, local officials said. A woman in her 70s in the adjacent city of Izumo sustained an injury in her leg after also falling out of her bed.