ASHEVILLE, N.C. — Floodwaters pushed by the remnants of Hurricane Helene left North Carolina’s largest mountain city isolated Saturday by damaged roads and a lack of power and cellphone service, part of a swath of destruction across southern Appalachia that left an unknown number dead and countless worried relatives unable to reach loved ones.

Gas shortages, downed power lines, spotty phone service and blocked roads made rescuing residents and assessing damage a nearly impossible task across much of western North Carolina, a day after Hurricane Helene drenched the region with historic amounts of rainfall.