At least 15 people went missing on Thursday and nearly 400,000 have been forced to evacuate their homes after huge floods swept away houses in southern Japan, tearing up roads as they surged through villages, government officials and media said.
The Japan Meteorological Agency officials have warned of worse situations to come as soldiers and rescuers scrambled to evacuate hundreds of thousands of people out of the path of landslides and torrents of muddy water.
"We are seeing heavy rains unlike anything experienced before," an official told Reuters. "It is an abnormal situation with serious danger looming."
The weather agency has issued warnings for landslides and overflowing rivers over wide swathes of Kyushu, the southernmost of Japan's four main islands. It added that heavy rainfall is likely to continue in the region through Friday.
NHK, the national broadcaster reported that parts of Fukuoka prefecture on the southwestern island of Kyushu were hit by 774 mm of rain in nine hours on Wednesday. According to reports, this is about 2.2 times the amount of rain that falls in a normal July.
Nearly 7,500 rescuers, including police, firefighters and soldiers from Japan's Self Defence Forces, were mobilised to help with evacuations and search for the missing people. The authorities said that 40 helicopters were on standby until the weather improved.
"There are many reports of people whose safety cannot be confirmed, things like 'a child was swept away by the river' and 'my house was swept away and I can't get in touch with my parents'," chief Cabinet secretary Yoshihide Suga told an emergency early morning news conference.
"We will keep in close contact with the disaster-hit areas and work with all our energy to save lives and ascertain the extent of the damage," he added.
Both Fukuoka and Oita prefectures, which are largely rural areas, were both the worst affected by the rainfall. It was caused due to a low pressure area on the Pacific Ocean that fed warm, moist air into Japan's seasonal rainy front.
The residents spent a worried night at evacuation centres set up at schools and government buildings on high ground amid reports of landslides and flooded roads. "It wasn't just the rain, there was thunder and lightning too. I couldn't see anything ahead of me," one woman at an evacuation centre told NHK.
A schoolboy, who was found sitting with his family told NHK: "I haven't heard from some of my friends, and I'm really worried."
However, there were no reports of any immediate reports of major transportation problems, but television footage showed a railway line left broken and twisted by floodwaters. Earlier this week, theTropical Storm Nanmadola affected the same area.