(Reuters) - The death toll in eastern Kentucky rose to at least 16 on Friday as flooding unleashed by "epic" torrential rainfall swept through homes, washed out roads and pushed rivers over their banks, state authorities said, warning that more fatalities were expected.

Police and National Guard troops, including personnel from neighboring states, used helicopters and boats to rescue dozens of people from homes and vehicles in Kentucky's Appalachian coal-mining region. Video from local media showed floodwaters reaching the roofs of houses and turning roads into rivers.

"This isn't over. While we're doing search and rescue, there are still real dangers out there," Governor Andy Beshear told a morning news conference.

After a helicopter flyover of the hardest-hit areas with Deanne Criswell, head of the U.S. Federal Emergency Management Agency, Beshear said he was stunned by the scope of the flooding.

Most of Jackson, a town of 2,200 people about 100 miles (160 km) southeast of Frankfort, the state capital, was submerged, he said.

"Hundreds of homes, their ballfields, their parks, businesses, under more water than I think any of us have ever seen in that area," he told reporters. "Just devastating."

The floods marked the second major national disaster to strike Kentucky in seven months, following a swarm of tornadoes that claimed nearly 80 lives in the western part of the state in December.

Beshear said the number of confirmed flood-related fatalities on Friday rose to 16 from 15, including at least six children, and that the death toll would almost certainly climb as floodwaters recede and search teams find more bodies.

"There's still a lot of people unaccounted for," he said, declining to quantify the number missing. "We may be updating the count of how many we lost for the next several weeks."

The floods resulted from downpours of 5 to 10 inches (13 to 25 cm) of rain that fell over the region in 24 hours, a deluge that may prove unprecedented in the region's record books, said William Haneberg, an environmental sciences professor and director of the Kentucky Geological Survey.

"It's a truly epic event," Haneberg said.

The disaster came two weeks after rain-triggered flash floods inundated the riverfront Appalachian community of Whitewood in southwestern Virginia near the Kentucky border.

The region's steep hillsides and narrow valleys make it prone to flooding, but the increasing frequency and severity of rain-caused floods in the Appalachian region are symptomatic of human-induced climate change, Haneberg said.

Flood events "are going to be more extreme and frequent, but it's hard to predict how extreme and how frequent they will be in the future," he said in an interview.