An elderly man and a young girl were killed, with several other people also in "cardiopulmonary arrest", after walls collapsed in a magnitude-6.1 quake that hit Osaka in western Japan on Monday, public broadcaster NHK said.
A 9-year-old girl and two men in their 80s are the first confirmed fatalities, according to the Associated Press.
The Fire and Disaster Management Agency said one person had no heartbeat and wasn't breathing and a second person also had no vital signs.
A strong quake knocked over walls and set off scattered fires around the city of Osaka Monday morning.
By Monday evening, bullet trains and some local trains had resumed operation, with stations swollen with commuters trying to get home, many of them waiting in long lines. Dozens of flights in and out of Osaka were grounded and train service was suspended across a wide area.
Japan coach Akira Nishino, who built his professional reputation coaching Gamba Osaka, said he and a number of his players have acquaintances or loved ones affected by Monday's quake, making for an unwelcome distraction on the eve of the team's Group H opener against Colombia in Saransk.
Passengers walk on railroad as the train service was suspended following an natural disaster in Takatsuki, Osaka, Monday, June 18, 2018.
The temblor occurred very close to the Arima-Takatsuki fault zone that extends about 55 kilometers from an area west of the Arima hot spring area in Kobe's Kita Ward, to the northern tip of downtown Takatsuki, Osaka Prefecture, agency officials said.
Several roads suffered severe damage and water pipes burst, sending water flowing onto streets in Takatsuki city where the biggest shock was felt.More news: Trump Dismisses IG Report’s Bias Conclusion as ‘Ridiculous’
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NHK showed footage of firefighters tackling a blaze that ripped through a home north of Osaka.
Gas has been cut off to more than 100,000 households in Osaka, while some 170,000 houses in Osaka and neighbouring Kyoto and Hyogo prefectures are left without power.
The magnitude 6.1 natural disaster struck north of Osaka city Monday shortly after 8 a.m. Two men in their 80s died after being hit by falling objects.
Many homes and buildings, including a major hospital, were temporarily without power, though electricity was restored at most places by midafternoon.
Several companies have suspended production at its factories in Osaka and Kyoto, including Panasonic, Daihatsu Motor Co, the Osaka-based unit of Toyota Motor Corp, and a joint venture plant by Sharp Corp and parent company Hon Hai Precision Industry.
Japanese soldiers joined rescue and relief operations in parts of Osaka, bringing special vehicles to deliver clean drinking water.
Eiji Shibuya, 52, said the tremor reminded him of the devastating 1995 Kobe quake, which killed almost 6,500 people.
The Osaka quake on Monday followed two tremors over the weekend. He said his wife ducked under a table and elevators in his office building were out of operation.
"The psychological impact is something I'm slightly anxious about at this point", Nishino said before Monday afternoon's training session.