Search and rescue teams were using boats and helicopters on Friday to look for survivors of flash floods caused by torrential rains which killed at least 16 people in the Appalachia region of eastern Kentucky.

Andy Beshear, governor of the south-central US state, warned that the death toll from the severe flooding was likely to "get a lot higher."

Homes submerged under flood waters from the North Fork of the Kentucky River are seen from a drone in Jackson, Kentucky
Homes submerged under flood waters from the North Fork of the Kentucky River are seen from a drone in Jackson, Kentucky AFP / LEANDRO LOZADA

Beshear said six of the 16 confirmed dead were children including four from the same family.

Kentucky National Guard helicopters, Fish and Wildlife boats and a flotilla of volunteers were scouring flood-hit areas on Friday for residents stranded on rooftops and even clinging on to trees.

A family looks at their submerged home in Jackson, Kentucky
A family looks at their submerged home in Jackson, Kentucky AFP / LEANDRO LOZADA

Hundreds of people have been rescued by boat since the flooding began Wednesday evening and there have been about 50 aerial rescues using National Guard helicopters, he said.

With many roads washed out "we still can't get to a lot of people," the governor said.

Aerial view of homes submerged under flood waters from the North Fork of the Kentucky River in Jackson, Kentucky
Aerial view of homes submerged under flood waters from the North Fork of the Kentucky River in Jackson, Kentucky AFP / LEANDRO LOZADA

"The current is so strong it's not safe for some of those water rescues that we need to do."

The impoverished Appalachia region of eastern Kentucky has had flash flooding previously, Beshear noted, "but we've never seen something like this."

"Folks who deal with this for a living, who have been doing it for 20 years, have never seen water this high," he said.

A bridge and a road are submerged by floodwaters from the North Fork of the Kentucky River in Jackson, Kentucky
A bridge and a road are submerged by floodwaters from the North Fork of the Kentucky River in Jackson, Kentucky AFP / LEANDRO LOZADA

"Some people's houses were completely swept away in the middle of the night while they were sleeping."

Some areas reported receiving more than eight inches (20 centimeters) of rain in a 24-hour period.

Members of a rescue team assist a family out of a boat in Quicksand, Kentucky, after flash floods
Members of a rescue team assist a family out of a boat in Quicksand, Kentucky, after flash floods GETTY IMAGES via AFP / Michael Swensen

The water level of the North Fork of the Kentucky River at Whitesburg rose to a staggering 20 feet within hours, well above its previous record of 14.7 feet.

The weather forecast for the next several days calls for a brief respite over the weekend with heavy rain predicted to resume on Monday.

Firefighters head out to  rescue people stranded by flooding in Lost Creek, Kentucky
Firefighters head out to rescue people stranded by flooding in Lost Creek, Kentucky GETTY IMAGES via AFP / Michael Swensen

Many roads resembled rivers and mangled cars and trucks littered the landscape or floated in muddy brown floodwaters.

Some houses were almost completely submerged in low-lying areas with just their rooftops visible.

Kayla Brown, 29, and Joe Salley Jr., 56, residents of Perry County, told the Lexington Herald-Leader that the fast-rising flood waters trapped them in their mobile home.

"It was like a wave coming at you out of the ocean," Salley said.

Neighbors came to their rescue after their trailer was knocked off its foundations.

Four young children ranging in age from one and a half to eight years old were swept away from their parents in hard-hit Knott County, the Herald-Leader reported.

Brittany Trejo, the siblings' cousin, told the newspaper their parents were rescued after clinging to a tree for eight hours.

"They managed to get to a tree and... held the children a few hours before a big tide came and washed them all away," Trejo said.

The eastern Kentucky flooding is the latest in a series of extreme weather events that scientists say are an unmistakable sign of climate change.

Nearly 60 people were killed in western Kentucky by a tornado in December 2021.

President Joe Biden has issued a disaster declaration for the Kentucky flooding, allowing federal aid to supplement state and local recovery efforts.

Deanne Criswell, head of the Federal Emergency Management Agency, took an aerial tour of flood-hit areas with the governor on Friday and will report back to the president.