A powerful aftershock that rocked an area of Japan still reeling from last month's earthquake and tsunami disaster killed three people and injured around 100, emergency services said.
The Fire and Disaster Management Agency said a 63-year-old woman in Yamagata prefecture died after her respirator failed when the power was knocked out by the 7.1 magnitude tremor.
"Her respiratory equipment was found turned off. We believe the machine was turned off due to the (power) outage," a spokesman for the agency said.
Reports said two men aged 79 and 85 were killed in Myagi prefecture - the area worst hit by the 9.0 magnitude quake of March 11 and the tsunami it spawned.
Broadcaster NHK said the 79-year-old was found unconscious after the quake and taken to hospital, where he was confirmed dead, while Jiji Press said an 85-year-old man also died in the quake, but gave no further details.
The disaster management agency said at least 93 people were confirmed injured while Jiji Press said about 130 were injured.
Power remains off for about 3.6 million households in the northeastern region, Jiji said.