Hurricane Dorian struck the northern Bahamas on Sunday as a catastrophic Category 5 storm, its 185 mph winds ripping off roofs and tearing down power lines as hundreds hunkered in schools, churches and other shelters.

The second-strongest Atlantic hurricane since 1950, Dorian hit land in Elbow Cay in the Abaco Islands after authorities made last-minute pleas for those in low-lying areas to evacuate. But officials recognized there were not many structures on higher ground on the largely flat archipelago southeast of Florida.

Millions from Florida to the Carolinas kept a wary eye on the slow-moving Dorian amid indications it would veer sharply northeastward after passing the Bahamas and track up the U.S. Southeast seaboard. But authorities warned that even if its core did not make U.S. landfall and stayed offshore, the potent storm would likely hammer U.S. coastal areas with powerful winds and heavy surf.

The National Hurricane Center in Miami said Dorian's maximum sustained winds at its 12:45 p.m. landfall were 185 mph (295 kph), up from 175 mph (281 kph). It was moving west at 7 mph (11 kph). "Catastrophic conditions" are occurring in The Abaco Islands and expected across Grand Bahama later in the day, the center said.

Dorian's power was second only to Hurricane Allen in 1980, with its 190 mph winds.

"It's going to be really, really bad for the Bahamas," Colorado State University hurricane researcher Phil Klotzbach said.

In the northern stretches of the Bahamas archipelago, hotels closed, residents boarded up homes and officials hired boats to move people to bigger islands as Dorian approached.

Bahamas Prime Minister Hubert Minnis warned that any "who do not evacuate are placing themselves in extreme danger and can expect a catastrophic consequence."

Still, dozens of people ignored evacuation orders, officials said, and they were warned that they were placing their lives in danger.

Among those refusing to leave were 32 people in Sweetings Cay, and a group that sought safety in Old Bahama Bay resort, which officials said was not safe.

Butler said officials were closing certain roads with heavy equipment and warned that those on the other side would be stranded until after Dorian has passed. The government has opened 14 shelters across the Bahamas.

Over two or three days, the slow-moving hurricane could dump as much as 4 feet (1 meter) of rain, unleash devastating winds and whip up a dangerous storm surge, said private meteorologist Ryan Maue, seconding some of the most reliable computer models.

Government spokesman Kevin Harris said Dorian was expected to affect 73,000 residents and 21,000 homes. Authorities closed airports for The Abaco Islands, Grand Bahama and Bimini, but Lynden Pindling International Airport in the capital of Nassau remained open.

Jeffrey Allen, who lives in Freeport on Grand Bahama, said he had learned after several storms that damage predictions sometimes don't materialize, but he still takes precautions.

"It's almost as if you wait with anticipation, hoping that it's never as bad as they say it will be. However, you prepare for the worst nonetheless," he said.

The Bahamas archipelago is frequently hit by hurricanes. Construction codes require homes to have metal reinforcements for roof beams to withstand winds into the upper limits of a Category 4 hurricane, and compliance is generally tight for residents who can afford it. Risks are higher in poorer communities, which typically have wooden homes and are generally in lower-lying areas.

The slow-crawling storm was predicted to take until Monday afternoon to pass over the Bahamas, and then turn sharply and skirt up the U.S. coast, staying just off Florida and Georgia on Tuesday and Wednesday and then buffeting South Carolina and North Carolina on Thursday.

The National Hurricane Center Sunday morning issued a hurricane watch for Florida's East Coast from Deerfield Beach north to the Volusia and Brevard county line. The same area was also put under a storm surge watch. Lake Okeechobee was put under a tropical storm watch.

Florida Gov. Ron DeSantis warned residents along the state's densely populated Atlantic coast: "We're not out of the woods yet."

Palm Beach County announced a mandatory evacuation for the eastern half of the county beginning at 1 p.m. Sunday after the morning forecast put the area in a tropical storm warning. The evacuation includes mobile homes, substandard housing, low-lying areas prone to flooding and homes along the Intracoastal Waterway and on barrier islands.

South Carolina Gov. Henry McMaster declared a state of emergency, mobilizing state resources to prepare for potential storm effects. President Donald Trump already declared a state of emergency and was briefed late Saturday about the storm.

The hurricane upended some Labor Day holiday weekend plans in the U.S.: Major airlines allowed travelers to change reservations without fees, big cruise lines rerouted their ships and Cumberland Island National Seashore off Georgia closed to visitors. Disney World and Orlando's other resorts held off announcing any closings.