A rapidly strengthening Hurricane Florence chugged across the Atlantic on Sunday toward a possible direct hit on the U.S. Southeast late this week, triggering warnings to people up and down the coast to get their emergency kits ready, map out escape routes and fill sandbags. Red flags flying on beaches warned swimmers to stay out of waters already roiled by the distant storm, and cruise ships and Navy vessels were being steered out of harm’s way. After briefly weakening to a tropical storm, Florence came roaring back as a Category 1 hurricane Sunday morning, climbing past the 74 mph threshold as it pushed westward about 700 miles southeast of Bermuda. Drawing energy from the warm water, it could be a fearsome Category 4 with winds of 130 mph or more by Tuesday, the National Hurricane Center said. The Miami-based hurricane center said that it is too early to know what path the storm will take, but that it could roll ashore in the Carolinas by Friday.The governors of North and South Carolina and Virginia declared states of emergency.Forecasters urged residents from South Carolina to the mid-Atlantic to get ready — and not just for a direct blow. They warned that Florence could slow or stall after coming ashore, with some forecasting models showing it could unload a foot or two of rain in places, causing devastating inland flooding. "Pretend, assume, presume that a major hurricane is going to hit right smack dab in the middle of South Carolina and is going to go way inshore," South Carolina Gov. Henry McMaster said. The state’s emergency management agency said it is "preparing for the possibility of a large-scale disaster." In Charleston, S.C., along the coast, city officials offered sandbags to residents. Myrtle Beach Mayor Brenda Bethune urged people to secure their homes but said it’s too early to know if evacuations will be ordered. In North Carolina, officials started getting bulldozers and chain saws ready, and people were urged to put together emergency supply kits, prepare their homes and research evacuation routes.Florence’s effects were already being felt along the coast, with dangerous swells and rip currents in some spots. On North Carolina’s Outer Banks, the town of Nags Head posted no-swimming flags on beaches. The Navy planned to send ships from the Hampton Roads area of Virginia out to sea. Florida-based Carnival Cruise Line re-routed its cruise ships.Meanwhile, Tropical Storm Isaac strengthened Sunday, with maximum sustained winds of 70 mph. Forecasters expected Isaac to become a hurricane by Sunday’s end and said it will move into the Caribbean on Thursday. Farther away, Tropical Storm Helene became Hurricane Helene on Sunday afternoon. Helene was about 145 miles southwest of the Cabo Verde Islands, off the coast of West Africa. The storm could bring 2-4 inches of rain to those islands, risking flash floods.