An elderly man and a young girl were killed on Monday (Jun 18) after a strong quake rocked Osaka in western Japan during the morning rush hour, the government said.
Top government spokesman Yoshihide Sugar confirmed the deaths, and said a third person was also feared dead.
"At this point we have information that two people died," he told reporters, adding that 20 people had been injured.
Local police said the child was a nine-year-old girl who died in the city of Takatsuki, north of Osaka city, with media reporting she was trapped when a wall collapsed on her at school.
Public broadcaster NHK said the man who was 80, had also been killed by a collapsing wall, and that the third fatality was a man trapped under a bookcase in his home.
The 5.3-magnitude quake struck at a depth of 15.4km, according to the United States Geological Survey. The Japanese meteorological agency originally put the quake's magnitude at 5.9 but later raised it to 6.1.
The epicentre of the earthquake was in the northern part of the prefecture at at a depth of 13km, the agency said. No tsunami warning was issued.
There were no immediate reports of major damage after the powerful quake which stranded commuters and left tens of thousands without power.
Prime Minister Shinzo Abe told reporters the government was "working united, with its first priority on saving people's lives".
"RING OF FIRE"
Local officials said they had not received reports of major damage in the highly urbanised area, where roads and train tracks criss-cross around densely packed apartment buildings.
NHK showed footage of firefighters tackling a blaze that ripped through a home north of Osaka, and several broadcasters showed images of water gushing into the street from underground pipes.
The quake struck at 8am (7am Singapore time), as platforms would have been heaving with passengers waiting to board their commuter trains to work.
A number of train services were suspended, including the "shinkansen" bullet train.
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 without power.
Despite its relatively low magnitude, the quake caused quite a shake, registering a lower six on the Japanese experiential scale of up to seven, meaning it is hard to stay standing.
"The floor moved violently. It was a strong vertical jolt. Nearly all of the dishes fell and shattered on the floor," said Kaori Iwakiri, a 50-year-old nurse in Moriguchi, just north of Osaka city.
"My parents suffered a blackout and they have no water. I plan to take water to them now."
Eiji Shibuya, 52, said the tremor reminded him of the devastating 1995 Kobe earthquake, which killed nearly 6,500 people.
"I was stunned. I couldn't do anything," he told reporters from Itami, a city in eastern Osaka region.
"I was worried about my son as he had just left for his high school. I was relieved when I confirmed he was safe."
POSSIBILITY OF AFTERSHOCKS
Multiple small aftershocks followed the quake, and an official from Japan's meteorological agency warned residents to remain on guard.
"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 agency.
And government spokesman Suga also cautioned "there is a possibility that strong aftershocks will happen."
"Large-scale quakes are likely to happen in the next two to three days," he told reporters.
Singaporean Benny Tong, who is in Osaka to visit his fiancee and her family, said he felt "intense rattling" for about 20 seconds before the quake.
"I could hear and feel the trembling of the house and furniture. Then the ground shook and swayed quite dramatically for about a minute. Thankfully nothing too bad happened.
"I could see the overhead electricity cables outside my house shake quite a lot. I have experienced a few minor quakes before in Osaka, but this was the first time I felt one as big as this," he said, adding that he usually visits Osaka every six months or so.
Japan sits on the so-called Pacific "Ring of Fire" where a large proportion of the world's earthquakes and volcanic eruptions are recorded.
On Mar 11, 2011, a devastating magnitude 9.0 quake struck under the Pacific Ocean, and the resulting tsunami caused widespread damage and claimed thousands of lives.
It also sent three reactors into meltdown at the Fukushima nuclear plant, causing Japan's worst postwar disaster and the most serious nuclear accident since Chernobyl in 1986.