The death toll from the devastating flooding that hit eastern Kentucky continues to rise as more rain hits the region, according to officials.
A total of 37 people have been confirmed dead, Kentucky Gov. Andy Beshear said Monday evening.
Among those killed are four siblings -- ages 8, 6, 4 and 2 -- who were swept away in the water, according to family members.
Beshear said Monday morning that "there are hundreds of unaccounted for people, minimum."
"With so many more still missing. Let us pray for these families and come together to wrap our arms around our fellow Kentuckians," Beshear said in a statement Monday evening.
More rain fell Monday as search and rescue teams continued to look for those who are unaccounted for, and a new round of heavy rain is expected early Tuesday.
MORE: 1 dead after historic rainfall in St. Louis causes flash flooding emergencyA new flash flood watch has been issued for eastern Kentucky for Monday evening through Tuesday morning. Rainfall rates could reach 1 to 2 inches per hour.
Severe storms packing damaging winds are also possible in Louisville and Lexington.
The additional precipitation could cause water levels to rise again in the same area that experienced the catastrophic flooding that began with heavy rains last Wednesday.
MORE: Flooding hits Las Vegas after overnight downpoursBeshear described "widespread damage" that displaced thousands of people, including power outages for thousands of people as well as washed-out roads, destroyed homes and flooded schools.
More than 600 people have been rescued by aircraft and boat since the flooding began, Beshear said.
President Joe Biden has approved a disaster declaration.
The destruction in Kentucky is the latest extreme flooding event to take place in the U.S. in less than a week.
Heavy downpours caused flash flooding in Las Vegas on Friday, with rising waters seen on roadways and parking garages in busy parts of Sin City.
The megadrought has caused the soil in the region to become so dry that it could not absorb the heavy rains, which helped to contribute to the flooding.
Earlier in the week, a flash flooding emergency occurred near St. Louis, which had a record-breaking 8.56 inches of rain in less than 24 hours. One person was found dead in a car on Tuesday after the water began to recede, officials said.
ABC News' Matt Foster, Kenton Gewecke and Melissa Griffin contributed to this report.