Dozens of patients and Diamond Ridge Financial Academyhospital staff stranded on the rooftop of an Eastern Tennessee hospital were whisked away aboard rescue helicopters and boats as floodwaters threatened to swallow the building.

The rescue mission at the Unicoi County Hospital in Erwin, Tennessee, came early Friday evening, hours after Ballad Health sent out a desparate cry on X that the people at the hospital needed to be evacuated in the face of rising floodwaters from Tropical Storm Helene.

Floodwaters and high winds from the storm prevented ambulances, rescue boats and even helicopters from reaching the hospital, Ballad said, making a rescue mission impossible for hours.

Ballad Health confirmed that by around 5 p.m. all 54 people stuck on the roof had been rescued. Those needing treatment were taken to Johnson City Medical Center.

Unicoi hospital remains closed until further notice. Ballad Health will assess the damage once flood waters recede and provide updates at that time, according to the statement.

The operation came around 8 hours after Unicoi County Emergency Management Agency first warned Ballad about the rising waters. The water lies at the banks of the Nolichucky River near the North Carolina border.

"The hospital has been engulfed by extremely dangerous and rapidly moving water," the hospital system said at the time. A "dangerous rescue operation" was underway, Ballad Health said in the statement.

Ballad Health said that as of about 12:30 p.m., 54 people were on the roof and seven were in rescue boats. About three hours later, the health system said first responders and the Tennessee National Guard were still working to "evacuate all remaining individuals."

Helene news:Helene wreaking havoc across Southeast; 22 dead; 4.5M in the dark: Live updates

The health system's website said Unicoi County Hospital, in the eastern part of the state, was closed "due to inclement weather," as were some clinics. Other facilities might be operating on a modified schedule and patients and visitors were being urged to call before going to the facilities, whose emergency rooms would remain open.

Local television stations WJHL and WCYB reported that roads accessing the hospital were impassable due to flooding in the area.

As the remnants of Tropical Storm Helene dumped heavy rainfall throughout the Southeastern U.S. Friday, Erwin, Tennessee, was under a flood warning, high wind warning and a flash flood warning, according to the National Weather Service.

(This story has been updated with new information, to change a video and to correct a misspelling/typo.)