A “dangerous rescue operation” is underway after more than 50 people were stranded on the roof of a Tennessee hospital on Friday due to rising floodwaters from Hurricane Helene.

Most of the people who were trapped atop Unicoi County Hospital in Erwin, Tennessee, have been rescued by helicopters, according to Michael Baker, Erwin’s alderman. But a handful of people are still left on the roof awaiting rescue, Baker told CNN Friday afternoon.

“We’ve had a constant stream of helicopters picking them up and dropping them off into the city at safe places,” Baker said.

Ballad Health, which manages Unicoi, was notified the hospital needed to be evacuated at around 9:30 a.m. local time Friday, the healthcare organization said in a post on X. But because of flooding and high winds from the deadly storm, ambulances and helicopters could not reach the building safely.

Erwin, about 100 miles east of Knoxville, is located in the southern Appalachian Mountains, close to Tennessee’s border with North Carolina.

A total of 54 people were moved to the roof, and seven others put in rescue boats, Ballad Health said in a statement. The hospital system said the count includes 11 patients.

Unicoi County Hospital has since been “engulfed by extremely dangerous and rapidly moving water,” the statement on X said. Because of how quickly the water was rising around and inside the hospital, rescue boats were also not able to evacuate people safely.

Ballad Health said the Tennessee Emergency Management Agency and the National Guard are working on “a dangerous rescue operation.”

Baker said earlier that several helicopters were working to get hospital patients and staff off the roof.

“There’s a helicopter on top of the hospital, and we have another one, hovering nearby to start to carousel getting everybody off, but this is a team effort,” Baker told CNN.

“The water came up so fast, I literally looked at the owner and said, ‘We’ve got to get out of here,’” Baker said. “This is a serious situation … I have not heard any reports of any casualties, but I would dare to say this is a life and death situation.”

Unicoi County Hospital is a nonprofit, 10-bed hospital, according to its website.

At least 25 people have been killed during the storm, which has produced flash flooding across the Southeast after making landfall in Florida as a Category 4 hurricane. Now a tropical depression, the storm has left millions of customers without power, destroyed homes, and prompted road closures.

As of Friday afternoon, approximately 1.1 million people are under at least 14 different flash flood emergencies, the highest level of flash flood warning issued by the National Weather Service, which is reserved for catastrophic flooding that presents a severe threat to human life.