Disastrous floods have left three dead and dozens missing in eastern Japan, authorities said Friday as thousands of rescuers were deployed to evacuate trapped residents from an inundated city north of Tokyo. 
The heaviest rain in decades pounded the country, threatening to worsen conditions in the wake of Typhoon Etau, which smashed through Japan earlier this week bringing strong winds and travel chaos.
At least 22 people, including a pair of eight-year-old children, were missing in disaster-struck Joso city, public broadcaster NHK said, quoting officials in the area which lies about 60 kilometres (37 miles) outside Tokyo. Another person was missing in a northern prefecture.
Joso, a community of 65,000 residents, was hammered Thursday when a levee on the Kinugawa river gave way, flooding an area that reportedly spans 32 square kilometres (12 square miles) and includes 6,500 homes.
Dramatic aerial footage showed whole houses being swept away by raging torrents in scenes eerily reminiscent of the devastating tsunami that crushed Japan's northeast coast four years ago.
Desperate Joso residents waved towels as they stood on balconies trying to summon help, while military dinghies ferried dozens of people to safety, and helicopters plucked individuals from rooftops.
Others took to social media on their smartphones to beg for help. 
Survivors of the flooding recounted horrific scenes as the muddy brown waves swirled around their doomed houses, while trees were uprooted and cars bobbed in the dirty water.
An evacuated Joso resident said she was anxiously awaiting details about her family at an emergency shelter, after leaving her husband and children to go shopping Thursday morning. She was unable to return home due to the flooding.
"I have been here since yesterday morning... and I do not have any news about my family," said the woman in her sixties who gave her last name as Furuya.
Top government spokesman Yoshihide Suga said some 5,800 troops, police and firefighters were dispatched early Friday to flooded areas where rescuers had worked through the night. 
- 'Ready to run away' - 
Television footage at daybreak from Joso, located in Ibaraki prefecture, showed city residents sloshing through knee-deep water to reach evacuation shelters, although waters as high as one-storey receded Friday.
The area has been hit by power outages and blackouts.
Another river in Miyagi prefecture, north of Ibaraki, burst its banks and flooded a populated area but many residents had already been evacuated, reports said.
In Kanuma city, north of Joso, a 63-year-old woman was killed after being swallowed by landslides triggered by the heavy rain, while a 48-year-old woman was also found dead in Miyagi, officials said.
Police said the third victim was a 25-year-old man who was helping to clean clogged drainage in the city of Nikko, which is known for its historic shrines. 
The heavy rains also affected those who are still in temporary shelters following the 2011 tsunami.
"I still feel the trauma" from the tsunami, a woman told public broadcaster NHK from a shelter in Minami Soma, one of the areas hit by the 2011 disaster that also triggered reactor meltdowns at the Fukushima nuclear plant.
"I was ready to run away as soon as the evacuation order was issued."
Flooding complicated a contaminated water problem at the crippled Fukushima plant, where the site's drainage pumps were overwhelmed, sending radiation-tainted water into the ocean.
By Friday, the lack of heavy rain in the area meant the pumps were no longer overwhelmed, said a spokesman for the site's operator.
Automaker Toyota temporarily shuttered three production plants in affected areas, citing employee safety, but said the facilities would restart them later Friday. The factories were not damaged.
An estimated 690 people were awaiting rescue as of 11:00 pm Thursday (1400 GMT), the National Police Agency said. It was not immediately clear how many people were currently trapped.
More than 100,000 people had been ordered to leave their homes on Thursday after the torrential rain, with up to 60 centimetres (two feet) falling in some places.
Forecasters from the Japan Meteorological Agency issued special warnings, urging vigilance against mudslides and flooding.
Japan is no stranger to natural disasters, and is frequently rocked by typhoons.
However, nothing in recent memory has compared with the tsunami of 2011, when more than 18,000 people were killed.
©  AFP