Angel Mitchell was in knots Friday morning at the eastern Tennessee hospital where her 83-year-old mother had been admitted days earlier for pneumonia.

While Mitchell and her brother visited their mother, who was undergoing tests at Unicoi County Hospital, she could hear urgent conversations among the nurses to evacuate the small facility in Erwin, nestled within the Blue Ridge Mountains east of Knoxville.

Follow live updates on the aftermath of Hurricane Helene

Remnants of Hurricane Helene were bringing catastrophic flooding across the Southeast.

But by the time the hospital started evacuations, Mitchell said, it appeared to be too late: Water overflowing from the nearby Nolichucky River was already rushing the building.

Over the next few hours, Mitchell's family and the dozens of others inside, including staff, patients and visitors, would be caught in a hazardous scenario — many racing to the roof and waiting to be rescued while the floodwaters perilously climbed.

Details from such harrowing events continue to emerge as officials grapple with a massive cleanup effort and communities come to terms with who and what was lost.

"I was more scared for my mom than I was for myself," Mitchell, 46, said Tuesday as she recalled how the ordeal nearly turned deadly.

"We all eventually started kind of panicking because water just kept rising, and we didn't know when we would get rescue to us," she said. "We all started kind of getting really scared that the whole building was going to be under [water] or it was going to collapse."

"We just thought, 'Oh, Lord, the building's going to collapse,'" she added.

Eventually, it took rescue boats and helicopter crews from the Tennessee Army National Guard and Virginia State Police to transfer people out safely.

Before then, Mitchell and her brother considered leaving the hospital by boats that were sent by the Tennessee Emergency Management Agency, but the fast-moving waters made getting across the parking lot too dangerous. They were ordered to go to the rooftop instead.

They waded through water and scrambled up ladders. That high up, about three stories, Mitchell could see ambulances and other cars getting swept away, and homes and debris floating by. A small aircraft was also pulled by the currents.

Ballad Health, the hospital's operator, said 54 people were brought to the roof at about 12:30 p.m. and needed to be rescued by air. High winds, however, made it unsafe for helicopters to fly.

About 11 patients needed to be evacuated, the hospital said.

Mitchell's mother, Janice Wilson, was among them. But instead of having patients clamber up ladders, they waited in lifeboats.

Mitchell said it was excruciating to watch her mother and other older patients waiting to be rescued. The blankets to keep them warm soaked in the muddy brown waters.

"I just had a fear that her pneumonia, that was going to kill her," Mitchell added.

People on the roof huddled together and braced themselves against the cold air. Some held hands and prayed. Mitchell accidentally dropped her phone in the water and had to borrow another to call her husband and three children.

When conditions improved, Black Hawk helicopters that could withstand the winds arrived. Mitchell said her mother was fastened to a gurney and hoisted up, then taken to another hospital.

Mitchell estimates it took about five hours for her to be rescued. During that last hour, a panic attack set in as she thought about her mother.

"It was luck that they came when they did because we only had 10 or 15 feet left before the whole rooftop would have been gone under" the water, she said.

Ballad Health said on its website that all patients were transferred to another facility about 15 miles away in Johnson City and that it would assess the damage in Erwin once the floodwaters recede.

In a statement Tuesday, the hospital system said Unicoi County emergency officials contacted it just before 9:40 a.m. Friday about a need to evacuate because of "unusually high and rising water," but as the process commenced, "the flooding of the property happened so quickly, the ambulances could not safely approach the hospital."

"Ballad Health immediately began procedures to evacuate as soon as local EMA notified us of the rising waters, as is protocol," a hospital system spokeswoman said in an email. "The river was flowing at a rate of 140,000 gallons per second — twice the rate of Niagara Falls."

While those at the hospital made it out safely, another business in Erwin, Impact Plastics, reported Monday that some workers had died and others were still missing amid the devastation.

Mitchell said she's grateful everyone at the hospital survived, but on Monday, her mother received another devastating diagnosis — that she has colon cancer.

After her mother previously survived breast cancer, Mitchell said she isn't sure how she will take to chemo treatment at her age.

"I'm better — I'm not going to die or anything," Mitchell said, "but my nerves are just all to pieces, especially finding that out about my mom."