A magnitude 6.1 earthquake rocked Japan's second city of Osaka on Monday, killing three people and injuring hundreds of others, according to an official tally and public broadcaster NHK.
Television images showed buildings swaying and burst pipes spewing water after the quake, which struck at the height of rush hour in the city of around two million people.
However, there was no large-scale destruction and no tsunami warning issued after the tremor, although commuters were stranded and tens of thousands were left without power.
Among the casualties was a nine-year-old girl who died in the city of Takatsuki, north of Osaka city, reportedly trapped by a collapsed wall.
NHK said an 80-year-old man had also been killed by a collapsing wall and another man trapped under a bookcase in his home.
In addition to the three deaths, it said more than 200 people were injured.
Prime Minister Shinzo Abe told reporters the government was "working united, with its first priority on saving people's lives".
And government spokesman Yoshihide Suga cautioned "there is a possibility that strong aftershocks will happen".
NHK showed footage of firefighters tackling a blaze that ripped through a home north of Osaka.
A number of train services were suspended, including the "shinkansen" bullet train, as multiple smaller aftershocks followed the quake.
The Nuclear Regulation Authority said it had detected no problems at its local atomic power plants, but some companies, including Honda, said they had suspended operations at local plants.
Kansai Electric said on its website that around 170,000 homes in the Osaka region were briefly without power.
"There are fears that the risk of house collapses and landslides has increased in the areas shaken strongly," said Toshiyuki Matsumori, in charge of monitoring quakes at the meteorological agency.
