West Virginia's three most devastated counties will receive federal assistance after the state's worst flooding in more than a century killed at least 24 people, officials said Saturday.

U.S. President Barack Obama declared a major disaster for West Virginia and ordered federal aid to affected individuals in Kanawha, Greenbrier and Nicholas counties that could include grants for temporary housing, repairs and other programs.

Obama spoke with West Virginia Gov. Earl Ray Tomblin on Saturday afternoon to give his condolences and make sure the governor has the federal resources he needs, White House spokesman Eric Schultz said.

West Virginia's death toll from flooding is the highest for any U.S. state this year, with 16 deaths reported in Greenbrier County in southeast West Virginia, where the heaviest rain fell, and six in Kanahwa County.

The Federal Emergency Management Agency (FEMA) and state officials were assessing damage in at least six other counties and the state may ask for additional assistance, Tomblin said.

Ohio and Jackson counties also reported one death each.

Ron Scott, right, looks over the burned remnants of his home that was swept off its foundation and burned after severe flooding hit the West Virginia community of White Sulphur Springs. (Steve Helber/Associated Press)

Up to 250 millimetres of rain fell on Thursday in the mountainous state, sending torrents of water from rivers and streams through homes causing widespread devastation.

Tomblin has declared a state of emergency in 44 of 55 counties and deployed 200 members of the West Virginia National Guard on Friday to help rescue efforts. About 32,000 homes and businesses remain without power.

Hundreds of people have been rescued and search-and-rescue teams were looking for more people on Saturday, said Tim Rock, spokesman for the state Division of Homeland Security and Emergency Management.

"There are going to be a lot of rebuilding, a lot of people without homes, a lot of businesses destroyed," Rock said.

Some towns were completely surrounded by water and hundreds of houses and buildings have been lost, Rock said.

Flooding in West Virginia had killed at least 26 people by Saturday morning. (West Virginia Department of Transportation via Reuters)

The Greenbrier resort was closed indefinitely and PGA Tour said Saturday they had cancelled the Greenbrier Classic golf tournament set to begin July 7 because extensive flooding damage could not be repaired in time.

West Virginia received one-quarter of its annual rainfall in a single day and multiple rivers surged to dangerous levels, including the Elk River, which broke a record at one stage that had stood since 1888.

'Where do we go now?'

Surrounded by muddy devastation, Cathy Light and her husband Chris thought it was "heaven sent" they had free burgers to munch on Saturday.

To their left, the roof of a Dairy Queen slumped to the ground. Behind it, a trailer home was ripped from its foundation, with four concrete stairs all that remained in the ground. Occasional whiffs of rotten food wafted from a nearby grocery store that, not long ago, was filled with five feet of muck water.

Before they jumped in a rescue boat in the town of Clendenin on Saturday, the Lights could only save their dog Odie and a TV that sat atop a bedroom dresser - the highest-up they stored anything in their house, really.

"I don't have anything," said Cathy Light, as she ate the free meal provided by Grace Community Church. "Where do we go now?"

Outstanding photo by <a href="https://twitter.com/ctrCGM">@ctrCGM</a> of the <a href="https://twitter.com/wvgazettemail">@wvgazettemail</a>. It says so much about what West Virginia is feeling right now. <a href="https://t.co/ACAxP6gcC2">pic.twitter.com/ACAxP6gcC2</a> —@RobByersWV