A police rescue team searches an earthquake-damaged house in Kumamoto, Japan, April 16, 2016. Taro Karibe/Getty Images

As the death toll topped 40 from two earthquakes this week in southwest Japan, government officials worried that the window of time to find survivors will soon run out. About 2,000 people were reported injured, about 190 of them seriously.

Heavy rain, combined with the risk of more aftershocks than the 130 to hit the area so far, has also hampered rescue efforts and ratcheted up fears of landslides. More than 240,000 people were told to evacuate areas at risk from landslides, the BBC reported.

"There are still sporadic aftershocks from this morning's earthquake, and so there is still a need to be vigilant," Yoshihide Suga, a government spokesman, told reporters Saturday. Search and rescue efforts have nevertheless continued into Sunday, NBC News reported.

Recent Earthquakes in Japan | FindTheData

The first, magnitude-6.4 earthquake struck Kumamoto Prefecture, located on the island of Kyushu, Thursday night, killing at least 16. The second quake, magnitude-7.3, rumbled through at 1:25 a.m. local time Saturday. Both wreaked havoc on roads, bridges and buildings and were followed by landslides in some areas. The quakes cut off more than 100,000 homes from power and left roughly 400,000 without water.

As troops, police and firefighters alike worked to hand out food and water, aftershocks continued. Public buildings that remained intact were transformed into temporary shelters for survivors. Others slept in their cars.

One risk of two successive earthquakes and their aftershocks is that buildings weakened or mildly damaged in the first could collapse entirely with the second.

The site of a landslide caused by an earthquake is seen in Minamiaso town in Kumamoto Prefecture in southern Japan, April 16, 2016. Kyodo/Reuters

Some 2,000 soldiers were involved in rescue and relief efforts. In one town, Mashiki, the Fire and Disaster Management Agency reported 66 people trapped in a nursing home.

In another instance, an 8-month-old girl was extracted Friday from the rubble of a house that had collapsed after Thursday's earthquake. It took 50 people and six hours of digging, but she was freed, uninjured.