Kentucky's governor predicted bodies will continue to be found "for weeks" as the death toll from devastating flooding rose Sunday to 28 and rescuers embarked on a long and grueling effort to locate victims.

Some areas in the mountainous region are still inaccessible following the flooding in the state's east that turned roads into rivers, washed out bridges and swept away houses. Off-and-on rain plus poor cell phone service are also complicating rescue efforts.

"This is one of the most devastating, deadly floods that we have seen in our history... And at a time that we're trying to dig out, it's raining," Governor Andy Beshear told NBC's "Meet the Press."

"We're going to work to go door to door, work to find, again, as many people as we can. We're even going to work through the rain. But the weather is complicating it."

The number of dead in the flooding, caused by torrential rain that began on Wednesday, is expected to rise even further.

"We're going to be finding bodies for weeks, many of them swept hundreds of yards, maybe a quarter mile-plus from where they were lost," Beshear said on "Meet the Press."

The governor toured flooded areas and made stops in three counties on Sunday. Across the rain-soaked portions of the state, more than 350 people are living temporarily in shelters, he said.

In the town of Jackson, the seat of hard-hit Breathitt County, state, local and federal rescue teams and aid workers fanned out.

Some were distributing water bottles to those in need. A boat marked "FEMA Rescue 4" sat on a trailer, indicating the presence of federal emergency crews.

Receding floodwaters had left a thick coating of dust on the streets as dark clouds presaged more rain ahead.

Some 35 miles (55 kilometres) south in the tiny community of Buckhorn, volunteers at a distribution centre told AFP that 700 to 800 people had come through on Sunday alone to collect donated supplies ranging from food to paper towels and toiletries.

The floods hit a region of Kentucky that was already suffering from grinding poverty -- driven by the decline of the coal industry that was the heart of its economy -- taking everything from people who could least afford it.

"It wiped out areas where people didn't have that much to begin with," Beshear said.

Threat of more flooding

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

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 National Weather Service's Weather Prediction Center warned of the potential for flooding in a swath of the United States, including central and eastern Kentucky, into Monday.

"The threat of flash flooding will continue through the afternoon and early evening hours from showers and thunderstorms with very heavy rainfall rates," it said in a forecast.

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

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 -- a disaster that Beshear said offered lessons for current efforts on the other end of the state.

"We learned a lot of lessons in western Kentucky on those devastating tornados about seven months ago, so we are providing as much support as we can and we are moving fast from all over the state to help out," he told CNN on Saturday.