Torrents of rainfall and flooding battered a widespread area in southwestern Japan on Saturday, with local media casualty reports climbing quickly. Public broadcaster NHK said 38 people were dead, four were injured seriously and 47 were missing.
Television footage showed a residential area in Okayama prefecture seeped in brown water spreading like a huge lake. Some people fled to rooftops and balconies and waved furiously at hovering rescue helicopters.
A seasonal rain front dumped record rain over a large area of western Japan, triggering landslides and flooding that hit homes and swept away cars, while authorities urged millions of residents to evacuate their homes.
At an emergency meeting, Prime Minister Shinzo Abe directed ministers to "prioritize lifesaving and send rescue crews without delay."
Okayama prefecture said a man caught in a landslide died, and six others were missing. Evacuation orders had been issued to more than 360,000 people, the prefecture said in a statement.
At least 21 people were confirmed dead in the western prefecture of Hiroshima, one of the hardest-hit areas, while 12 were killed in Ehime on the south-western island of Shikoku, NHK said.
Throughout the affected areas, parked cars sat in pools of water. NHK TV said water had reached as high as 5 meters (16 feet) in the worst-hit areas.
Kyodo news service, which put the death tally at 34 people, said one death was in a landslide in Hiroshima, which had set off a fire, while the body of a child was found in another area. NHK said a woman died in her home in Hiroshima when it got buried in a mudslide.
Assessing overall casualties was a challenge because of the widespread damage. NHK repeatedly urged those awaiting rescue to not lose hope.
In Ehime prefecture, a woman was found dead on the second floor of a home hit by a landslide, Kyodo said. Also in Ehime, two elementary-school girls and their mother who got sucked into a mudslide were rescued but their hearts weren't beating, it said.
Kyoto prefecture said it was working to control flooding at several dams and identified one fatality as a 52-year-old woman.
Military water trucks were rushing to areas where water systems were no longer working, Okayama prefecture said. Troops in camouflage outfits helped people and pets reach dry land on small military boats.
Evacuation orders or advisories were sent for 4.72 million people, and 48,000 members of the Self-Defense Forces, police and firefighters were mobilized for search missions, according to Kyodo.
Earlier this week, Typhoon Prapiroon hit south-western Japan, leaving one dead and about 20 injured.
The Japan Meteorological Agency upgraded its alert system to the highest level -- only issued when the amount of rain is expected to be the highest in decades -- in large areas of western Japan, while lifting the warning in other regions.
Agency official Minako Sakurai told reporters heavy rain was forecast to continue until Sunday in western and eastern Japan.