North Carolina’s governor said that the death toll of 11 from Hurricane Helene is expected to rise as rescuers and other emergency workers reach areas currently isolated by collapsed roads, failing infrastructure and widespread flooding.

“This is an unprecedented tragedy that requires an unprecedented response,” governor Roy Cooper said at a press conference on Sunday.

He added that “we know there will be more” deaths and he asked residents to avoid traveling on roadways in western North Carolina not only to avoid dangers but to keep roads clear for emergency vehicles.

More than 50 search teams have fanned out across the region in search of stranded people.

“Many people are cut off because the roads are impassable,” he said. Supplies were being airlifted to the region around Asheville, a city tucked in the western North Carolina mountains known for its arts, culture and natural beauty.

The rescue efforts included saving 41 people in one mission north of Asheville and an infant. The teams were finding people through both 911 calls and messages on social media, North Carolina adjutant general Todd Hunt said.

Hurricane Helene roared ashore in Florida’s Big Bend region as a Category 4 hurricane late on Thursday with winds of 140 mph.

From there, it quickly moved through Georgia, where governor Brian Kemp said on Saturday that it “looks like a bomb went off” after viewing splintered homes and debris-covered highways from the air.

Weakened, Helene then soaked the Carolinas and Tennessee with torrential rains, sending creeks and rivers over their banks and straining dams.

More than 60 people have been killed. Several million people were without power as of Sunday afternoon.

In Texas, Jessica Drye Turner begged for someone to rescue her family members stranded on their rooftop in Asheville, surrounded by rising flood waters.

“They are watching 18 wheelers and cars floating by,” Ms Turner wrote in an urgent Facebook post on Friday.

But in a follow-up message, which became widely circulated on social media on Saturday, Ms Turner said help had not arrived in time to save her parents, both in their 70s, and her six-year-old nephew. The roof had collapsed and the three drowned.

“I cannot convey in words the sorrow, heartbreak and devastation my sisters and I are going through nor imagine the pain before us,” she wrote.

Western North Carolina was isolated because of landslides and flooding that forced the closure of Interstate 40 and other roads.

There have been hundreds of water rescues, none more dramatic than in rural Unicoi County in East Tennessee, where dozens of patients and staff were plucked by helicopter from a hospital rooftop on Friday.

The storm was expected to hover over the Tennessee Valley on Saturday and Sunday, the National Hurricane Centre said.

It unleashed the worst flooding in a century in North Carolina.

One community, Spruce Pine, was doused with over 24 inches (60cm) of rain from Tuesday through Saturday.

In Atlanta, 11 inches (28cm) of rain fell over 48 hours, the most the city has seen over two days since record keeping began in 1878.

Among the 11 confirmed deaths in Florida were nine people who drowned in their homes in a mandatory evacuation area on the Gulf Coast in Pinellas County, sheriff Bob Gualtieri said.

Climate change has exacerbated conditions that allow such storms to thrive, rapidly intensifying in warming waters and turning into powerful cyclones sometimes in a matter of hours.

Helene was the eighth named storm of the Atlantic hurricane season, which began June 1.

The National Oceanic and Atmospheric Administration has predicted an above-average season this year because of record, warm, ocean temperatures.