WILMINGTON, N.C. — Through dark, flooded streets, Leonard Harrison, a volunteer with the United Cajun Navy, guided a rescue boat searching for people stranded by the powerful storm, Florence. Dozens of volunteers, many of whom arrived in trucks with boats in tow, watched the storm’s progress and rising waters, knowing they would soon receive calls for help.

The loosely organized assembly of weekend fishermen, shift workers, college students and others has come to the rescue before, in storms like Hurricane Katrina in 2005 and Hurricane Harvey last year. This time, the volunteers spread out across Florence’s path.

On Saturday night, a call came about a family in need of help in Wilmington.