The death toll from flooding and mudslides caused by torrential rain on the Japanese island of Kyushu rose to 15 on Friday as rescue workers battled to save anyone trapped alive in damaged or destroyed buildings.

The victims included a pregnant woman reportedly found holding her little boy in a house swept away by floodwater in Asakura, Fukuoka Prefecture, one of the hardest-hit areas by Wednesday's downpour.

A flood warning has been issued for Kitakyushu, Fukuoka, while evacuation orders remained in place in Fukuoka, Oita and Kumamoto prefectures. At one point, an evacuation order was issued to 49,000 people in Kitakyushu.

Rescue workers continued searching for the missing, with at least 20 people unaccounted for in Fukuoka and Oita where all the casualties were found.

Around 2,200 people were taking shelter in Fukuoka and Oita on Friday. At an elementary school in Asakura, around 180 people, including many elderly people, took refuge, with some asking for warm meals and change of clothes.

Around 20 hamlets in mountainous areas of Fukuoka were isolated as road access was severed. Helicopters were sent to rescue people in those areas, with the operation expected to take time as the choppers can carry only so many people.

Rain was forecast to continue through Saturday in these prefectures and other areas in the southwest, according to the Japan Meteorological Agency.

GALLERY: Torrential rain batters southwestern Japan

VIDEO: Drone footage shows extent of flooding in Kyushu

The government stepped up its rescue effort by dispatching 12,000 Self-Defense Force members, police officers and firefighters.

The pregnant woman found dead clutching her young son is believed to have been visiting her parents' home in Asakura. The house was swept about 10 meters off its foundation and its first floor totally collapsed. The body of her mother was also found nearby, and a neighbor said he heard a rescue worker say the boy was found dead in his mother's arms.

Also in Asakura, the body of Tetsuo Fujimoto, 66, was found under driftwood; the bodies of Toshihiko Kato, 87, and his wife Mikiko, 85, were found near a wrecked house; and a 21-year-old man was found dead near a river.

In the neighboring village of Toho where damage was also extensive, the body of a man was recovered, according to the village.

In Oita's Hita, Taketo Yamamoto, a 43-year-old firefighter, was found dead after being swept away by a mudslide. Two other people were found dead in the city.

Emperor Akihito and Empress Michiko expressed their sympathy to the governors of the heavily affected prefectures of Fukuoka and Oita in the wake of the torrential rain, according to the Imperial Household Agency.


The imperial couple also said they were saddened by the damage in Kumamoto, especially as it comes at a time when the area is still trying to recover from the impact of earthquakes in April last year.

The torrential rain and ensuing disaster have also delayed the announcement of the engagement of Princess Mako, the eldest granddaughter of the imperial couple, originally scheduled for Saturday.

To assess the damage, a government survey team headed by disaster management minister Jun Matsumoto was sent to Fukuoka on Friday. The government plans to send it to Oita on Sunday.

"I want ministers to show their leadership for restoration and prevention of further damage," Chief Cabinet Secretary Yoshihide Suga said Friday at a ministerial meeting to tackle the disaster.

Although emergency warnings have been lifted, the weather agency continued to urge residents to stay vigilant for mudslides due to ground being loosened by a third straight day of rain Friday.

Rainfalls of over 50 millimeters in an hour were recorded in Fukuoka, Nagasaki and Kumamoto prefectures early Friday.

Weather conditions remained very unstable in western Japan as moist air seeped toward a seasonal rain front staying over the Tsushima Strait between Japan's southwest and South Korea, the weather agency said.

Traffic remained disrupted in wide areas of Kyushu, with expressways partially blocked and JR Kyushu, the major railway operator in the region, partially suspending services on some lines. Around 2,000 households in Fukuoka and Oita remain without power and phone and internet service were also cut in some areas.

In Fukuoka, 215 houses are reported to have been destroyed or damaged, while 81 sections of roads, 17 bridges and 45 stretches of river were found damaged. In Oita, 158 buildings, 145 road parts and 27 river sections were damaged.

The number of evacuees totaled 1,585 in Fukuoka and 615 in Oita.