Forecasts of more heavy rains in western Japan have raised the risk of further landslides in Hiroshima, hindering efforts to locate dozens of people still missing after hills around the city collapsed earlier this week.
The Fire and Disaster Management Agency on Friday said 40 people were confirmed dead and 47 were unaccounted for after torrents of mud, rocks and timber swept through at least five valleys in Hiroshima's suburbs after heavy rains early on Wednesday.
Dozens more were injured, while among those killed was a rescue worker who was swept away by sliding land while trying to rescue a three-year-old boy, who also died.
Noriyoshi Masaoka, a 53-year-old firefighter, was still holding the boy in his arms when they were dug up from beneath the mud.
"He risked his life, he worked so hard," Hiroshima Mayor Kazumi Matsui told a news conference, his voice trembling, the AP news agency reported. "I treasure my staff who devote themselves to other people."
About 2,800 police and military personnel have been searching for the victims, at times suspending their work to reduce risks from further slides.
Rescue workers said the massive amounts of mud slowed them down, while narrow alleyways in the area made it difficult to use heavy machinery to remove debris.
Matsui asked rescue workers to do their utmost over the next few hours, noting that the chances of finding survivors drop after about 72 hours.
Authorities issued evacuation orders on Friday for 4,386 people in the city of Hiroshima due to fears of further danger, and a warning for 164,000 others.
The disaster has prompted questions over why so many houses were built near unstable slopes and why an evacuation advisory came an hour after the first mudslide on Wednesday.
Matsui said city officials initially thought the torrential rain was in limited areas and were reluctant to order an evacuation that might be a false alarm in the middle of the night.