A Japanese city was flooded Thursday when a raging river burst its banks, destroying homes and cars as desperate residents waited for help, and as thousands of people were ordered to evacuate.

Dramatic television footage showed a wall of muddy water gushing from the swollen Kinugawa river in Joso city, north of Tokyo, which is home to around 65,000 people.

Several people are reportedly missing across the country as waist-high floods in some areas left rescuers scrambling to pluck residents to safety as a wide area was deluged in the wake of Typhoon Etau.

The huge rains also exacerbated a contaminated water problem at the crippled Fukushima nuclear plant as it overwhelmed the site's drainage pumps, sending radiation-tainted water into the ocean.
"This is a scale of downpour that we have not experienced before," forecaster Takuya Deshimaru told an emergency press conference.

Prime Minister Shinzo Abe said the government was on high alert.

"The government will stand united and do its best to deal with the disaster... by putting its highest priority on people's lives," he told reporters.

In Joso, houses and vehicles were washed away along with some power lines, as military personnel headed to the area to help with the rescue mission.

A solitary man clutched onto a concrete power pole, unable to move as raging water surged by him. He was later rescued.

Nearby, an emergency official was suspended from a helicopter to rescue a person from a submerged home.
Desperate residents waved towels at rescuers as they stood on second-floor balconies waiting for help.

"Please continue to ask for help. Please do not give up hope," an NHK broadcaster said in an apparent message to helpless residents.

The city is about 60 kilometres (37 miles) outside the capital Tokyo, which has also been hit by flooding.

- Buried by landslides -

Joso is in Ibaraki prefecture, where the Japan Meteorological Agency had issued special warnings urging vigilance against mudslides and flooding. It had similar warnings for Tochigi prefecture.
"The prefecture has requested assistance from the Self-Defence Forces and police helicopters from the region. We are receiving their help," a prefectural official told AFP.

"We do not have updated information about the damage, but we know it is extensive and affected wide areas," he added.

Tochigi authorities ordered more than 90,000 residents to evacuate, while another 116,000 were advised to leave their homes, public broadcaster NHK said. In Ibaraki , at least 20,000 were ordered to evacuate for fears of floodings.

In Tochigi's Kanuma city, a local official said rescuers were searching for a missing person believed to be buried in mudslides.

"We don't know details of this person yet," he said.
NHK reported it was a woman in her 60s buried after mudslides destroyed houses. Her husband was rescued soon after, it added.

Two men were missing in Nikko, a city known for its historical shrines, after possibly being buried by landslides, public broadcaster NHK said.

Two other men in Nikko were rescued after being swept into a drainage gutter, but one was unconscious, the broadcaster said.

Etau, which smashed into Japan on Wednesday, moved out into the Sea of Japan (East Sea) by the end of the day, but a wall of rain continued to lash the country.

More than a dozen people were injured, including a 77-year-old woman who broke her leg after falling in strong winds, local reports said.