Even as millions across Texas picked up the pieces after Hurricane Harvey, which battered that region with record-setting rain last week and was blamed for at least 60 deaths, Hurricane Irma gathered strength in the ocean, registering as a Category 5 with winds in excess of 180 miles per hour.

Concern centered particularly on the Florida Keys, a chain of islands at the southern tip of the state that is a tourist hot spot and home to more than 80,000 residents. It is in the direct path of the storm as currently forecast, leading local officials there to announce that the area would be under mandatory evacuation orders beginning Wednesday.

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Fear also spread north into Miami-Dade, the state’s most populous county with 2.7 million residents. Though the storm’s exact trajectory was still unknown, Miami-Dade Mayor Carlos A. Gimenez urged residents to stock up on food and water and warned that evacuation orders could follow in some areas. The county already planned to start evacuating those with special needs on Wednesday.

“This hurricane is far too powerful, poses far too great a threat, for us to delay actions any further,” Gimenez said at a news briefing Tuesday afternoon. “I would rather inconvenience our residents on this occasion than suffer any unnecessary loss of life if in fact we are hit by Hurricane Irma. It is still too early to know if we will take a direct hit.”

Forecasters on Tuesday called Irma one of the strongest hurricanes ever recorded in the Atlantic. The National Hurricane Center warned of “large and destructive waves” along the coasts of Haiti, the Dominican Republic and the Bahamas, while also saying that flooding could drench parts of Puerto Rico and the British and U.S. Virgin Islands. Puerto Rico’s governor on Tuesday asked President Trump to declare a state of emergency ahead of the storm’s arrival.

epa06186470 Palm trees flutter due to wind and rain in San Juan, Puerto Rico, 05 September 2017. Puerto Rico is taking measures ahead of the passage of Hurricane Irma, which is on the verge of impacting the Caribbean Lesser Antilles as it reached the maximum level of category 5. EPA-EFE/Thais Llorca (Thais Llorca/Epa-Efe) CORRECTS CITY - Cyber School Supply Christopher Rodriguez is supported as he installs wood panels over a storefront window in preparation for Hurricane Irma, in Toa Baja, Puerto Rico, Tuesday, Sept. 5, 2017. Irma grew into a dangerous Category 5 storm, the most powerful seen in the Atlantic in over a decade, and roared toward islands in the northeast Caribbean Tuesday. (AP Photo/Carlos Giusti) Men cover the windows of a auto parts store in preparation for Hurricane Irma, in San Juan, Puerto Rico September 5, 2017. REUTERS/Alvin Baez (Alvin Baez/Reuters) TAMPA, FL - SEPTEMBER 05: Residents work together to fill sandbags for each other at Bobby Hicks Park as residents prepare ahead of Hurricane Irma on September 5, 2017 in Tampa, Florida. The National Hurricane Center (NHC) has reported that Hurricane Irma has strengthened to a Category 5 storm as it crosses into the Caribbean and is expected to move on towards Florida. (Brian Blanco/Getty Images) People buy material as part of preparations for arrival of Hurricane Irma on September 4, 2017 in Marigot, on the French overseas island of Saint-Martin. / AFP PHOTO / Lionel CHAMOISEAULIONEL CHAMOISEAU/AFP/Getty Images (Lionel Chamoiseau/AFP/Getty Images) Hurricane Irma, a category 4 hurricane with maximum sustained winds near 150 mph (240 km/h) with higher gusts, is shown in this GOES satellite image in the Atlantic Ocean east of the Leeward Islands and Puerto Rico and the Dominican Republic, September 5, 2017. U.S. Navy photo/Handout via REUTERS ATTENTION EDITORS - THIS IMAGE WAS PROVIDED BY A THIRD PARTY (Us Navy/U.S. Navy) Windows of a car dealer are protected by tape and sandbags, on September 4, 2017 in Marigot, on the French overseas island of Saint-Martin, as part of preparations ahead of the arrival of Hurricane Irma. / AFP PHOTO / Lionel CHAMOISEAULIONEL CHAMOISEAU/AFP/Getty Images (Lionel Chamoiseau/AFP/Getty Images) A woman looks at empty shelves that are normally filled with bottles of water after Puerto Rico Governor Ricardo Rossello declared a state of emergency in preparation for Hurricane Irma, in San Juan, Puerto Rico September 4, 2017. REUTERS/Alvin Baez (Alvin Baez/Reuters) Cars line up for gas on Philips Highway at Baymeadows Road in Jacksonville, Fla., Tuesday, Sept. 5, 2017. The U.S. National Hurricane Center says the Category 5 storm has winds of up to 185 mph (297 kph) as it approaches the Leeward Islands of the northeast Caribbean. (Will Dickey/The Florida Times-Union via AP) (Will Dickey--/AP) Shoppers in a Home Depot store wait for plywood in the Little Havana neighborhood in Miami, Florida, September 5, 2017. Residents are preparing for the approach of Hurricane Irma. REUTERS/Joe Skipper (Joe Skipper/Reuters) A man stops vehicular transit while a boat lifter transports a boat to a safer area as hurricane Irma approaches Puerto Rico in Fajardo, on September 5, 2017. In Puerto Rico, a US territory of 3.5 million, Governor Ricardo Rossello activated the National Guard and announced the opening of storm shelters able to house up to 62,000 people. The major of the Puerto Rican capital San Juan, Carmen Yulin Cruz Soto, ordered 900 municipal employees -- police, emergency personnel, and aid and social workers -- to report for rotating 12-hour shifts.Even if Puerto Rico is spared a direct hit, the mayor said, three days of pounding rain will do heavy damage. / AFP PHOTO / Ricardo ARDUENGORICARDO ARDUENGO/AFP/Getty Images (Ricardo Arduengo/AFP/Getty Images) People queue at a supermarket as they buy goods as part of preparations ahead of the arrival of Hurricane Irma on September 5, 2017, in the French overseas island of Guadeloupe. Irma picked up strength and has become an "extremely dangerous" Category Five hurricane as it approached the Caribbean on September 5, the Miami-based National Hurricane Center reported. The monster hurricane, the most powerful of the five-level Saffir-Simpson scale, is about 270 miles (440 kilometers) east of the island of Antigua packing maximum sustained winds of 175 miles (280 kilometers) per hour. / AFP PHOTO / Helene VALENZUELAHELENE VALENZUELA/AFP/Getty Images (Helene Valenzuela/AFP/Getty Images) A man boards up his door as part of preparations ahead of the arrival of Hurricane Irma on September 5, 2017, in the French overseas island of Guadeloupe. Irma picked up strength and has become an "extremely dangerous" Category Five hurricane as it approached the Caribbean on September 5, the Miami-based National Hurricane Center reported. The monster hurricane, the most powerful of the five-level Saffir-Simpson scale, is about 270 miles (440 kilometers) east of the island of Antigua packing maximum sustained winds of 175 miles (280 kilometers) per hour. / AFP PHOTO / Helene VALENZUELAHELENE VALENZUELA/AFP/Getty Images (Helene Valenzuela/AFP/Getty Images) Residents purchase water at BJ Wholesale in preparation for Hurricane Irma Tuesday, Sept. 5, 2017, in Miami. Hurricane Irma grew into a dangerous Category 5 storm, the most powerful seen in the Atlantic in over a decade, and roared toward islands in the northeast Caribbean Tuesday on a path that could eventually take it to the United States. (Roberto Koltun/Miami Herald via AP) Jackie Kreuter, 56, of Gulfport, Fla., tosses pool furniture in the pool Tuesday, Sept. 5, 2017 so it doesn't fly around during the impending hurricane. Kreuter, along with her mother, husband, sister, daughter, grandson, five dogs and a bird are boarding up their home and business and leaving for Ocala to get out of Hurricane Irma's way. (Lara Cerri/The Tampa Bay Times via AP) Workers from a hardware store secure plywoods on top of a car as hurricane Irma approaches Puerto Rico in Bayamon, on September 5, 2017. In Puerto Rico, a US territory of 3.5 million, Governor Ricardo Rossello activated the National Guard and announced the opening of storm shelters able to house up to 62,000 people. The major of the Puerto Rican capital San Juan, Carmen Yulin Cruz Soto, ordered 900 municipal employees -- police, emergency personnel, and aid and social workers -- to report for rotating 12-hour shifts.Even if Puerto Rico is spared a direct hit, the mayor said, three days of pounding rain will do heavy damage. / AFP PHOTO / Ricardo ARDUENGORICARDO ARDUENGO/AFP/Getty Images (Ricardo Arduengo/AFP/Getty Images) TOPSHOT - A man rides past a boarded up house as part of preparations ahead of the arrival of Hurricane Irma on September 5, 2017, in the French overseas island of Guadeloupe. Irma picked up strength and has become an "extremely dangerous" Category Five hurricane as it approached the Caribbean on September 5, the Miami-based National Hurricane Center reported. The monster hurricane, the most powerful of the five-level Saffir-Simpson scale, is about 270 miles (440 kilometers) east of the island of Antigua packing maximum sustained winds of 175 miles (280 kilometers) per hour. / AFP PHOTO / Helene VALENZUELAHELENE VALENZUELA/AFP/Getty Images (Helene Valenzuela/AFP/Getty Images) Motorists head north on US Route 1 as Hurricane Irma moves its path in the northeast Caribbean, Tuesday, Sept. 5, 2017, in Key Largo, Fla. Wielding the most powerful winds ever recorded for a storm in the Atlantic Ocean, Hurricane Irma bore down Tuesday on the Leeward Islands of the northeast Caribbean on a forecast path that could take it toward Florida over the weekend. (AP Photo/Alan Diaz) Eduardo Soriano of Miami, waits in a line since dawn to purchase plywood sheets at a Home Depot store in North Miami, Fla., Wednesday, Sept. 6, 2017. Florida residents are preparing for the possible landfall of Hurricane Irma, the most powerful Atlantic Ocean hurricane in recorded history. (AP Photo/Marta Lavandier) In preparation of Hurricane Irma, residents of Boca Raton line up for propane in Boca Raton, Florida, U.S., September 6, 2017. REUTERS/Joe Skipper (Joe Skipper/Reuters) epa06187905 Miami residents are buying supplies to be prepared for Hurricane Irma in Miami, Florida, USA, 06 September 2017. Florida governor Rick Scott has issued a state of emergency as Hurricane is expected to affect Florida on 09 September 2017. EPA-EFE/CRISTOBAL HERRERA (Cristobal Herrera/Epa-Efe) Police patrol the area as Hurricane Irma slams across islands in the northern Caribbean on Wednesday, in San Juan, Puerto Rico September 6, 2017. REUTERS/Alvin Baez TPX IMAGES OF THE DAY (Alvin Baez/Reuters) Drivers wait in line for gasoline in Altamonte Springs, Fla., ahead of the anticipated arrival of Hurricane Irma, Wednesday, Sept. 6, 2017. Irma roared into the Caribbean with record force early Wednesday, its 185-mph winds shaking homes and flooding buildings on a chain of small islands along a path toward Puerto Rico, Cuba and Hispaniola and a possible direct hit on densely populated South Florida. (Joe Burbank/Orlando Sentinel via AP) Motorists head north on US 1, Wednesday, Sept. 6, 2017, in Key Largo, Fla., in anticipation of Hurricane Irma. Keys officials announced a mandatory evacuation Wednesday for visitors, with residents being told to leave the next day. (AP Photo/Alan Diaz) epa06188006 Miami residents are buying water and supplies to be prepared for Hurricane Irma in Miami, Florida, USA, 06 September 2017. Florida governor Rick Scott has issued a state of emergency as Hurricane is expected to affect Florida on 09 September 2017. EPA-EFE/CRISTOBAL HERRERA (Cristobal Herrera/Epa-Efe) MIAMI, FL - SEPTEMBER 06: Winston Mora and Gus Sousa (L-R) put hurricane shutters on a business as they prepare for Hurricane Irma on September 6, 2017 in Miami, Florida. It's still too early to know where the direct impact of the hurricane will take place but the state of Florida is in the area of possible landfall. (Joe Raedle/Getty Images) General view of half-submerged vehicles, boats and debris in the flooded harbour as Hurricane Irma hits the French island territory of Saint Martin September 6, 2017, in this video grab made from footage taken from social media. Mandatory credit RCI GUADELOUPE/Handout via REUTERS ATTENTION EDITORS - THIS IMAGE HAS BEEN SUPPLIED BY A THIRD PARTY. NO RESALES. NO ARCHIVE. REUTERS IS UNABLE TO INDEPENDENTLY VERIFY THE AUTHENTICITY, CONTENT, LOCATION OR DATE OF THIS IMAGE. (Social Media/Reuters) MIAMI, FL - SEPTEMBER 06: A sign on a business reas, 'Be Prepared Go Away Irma,' as people prepare for the arrival of Hurricane Irma on September 6, 2017 in Miami, Florida. It's still too early to know where the direct impact of the hurricane will take place but the state of Florida is in the area of possible landfall. (Joe Raedle/Getty Images) DORAL, FL - SEPTEMBER 06: Florida Governor Rick Scott gives an update to the media regarding Hurricane Irma on September 6, 2017 in Doral, Florida. It's still too early to know where the direct impact of the hurricane will take place but the state of Florida is in the area of possible landfall. (Mark Wilson/Getty Images) A member of the Emergency Operations Committee (COE) monitors the trajectory of Hurricane Irma in Santo Domingo, Dominican Republic, September 6, 2017. REUTERS/Ricardo Rojas (Ricardo Rojas/Reuters) Hurricane Irma, a record Category 5 storm, is seen approaching Puerto Rico in this NOAA National Weather Service National Hurricane Center satellite image taken on September 6, 2017. Courtesy NOAA National Weather Service National Hurricane Center/Handout via REUTERS ATTENTION EDITORS - THIS IMAGE WAS PROVIDED BY A THIRD PARTY (Noaa/Reuters) People take shelter in a school as Hurricane Irma slammed across islands in the northern Caribbean on Wednesday, in Fajardo, Puerto Rico September 6, 2017. REUTERS/Alvin Baez (Alvin Baez/Reuters) Search and rescue crew members clears a fallen tree during a search mission as hurricane Irma hits Puerto Rico in Fajardo on September 6, 2017. Irma is expected to reach the Virgin Islands and Puerto Rico by nightfall on September 6. / AFP PHOTO / Ricardo ARDUENGORICARDO ARDUENGO/AFP/Getty Images (Ricardo Arduengo/AFP/Getty Images) James Byrd, left, and Richard Clark, right, load their sandbags in a truck Wednesday, Sept. 6, 2017, at Newtown Estates Recreation Center in Sarasota, Fla., as they prepare for Hurricane Irma. The each got their ten bags before Sarasota County ran out of sandbags for residents. The county still has plenty of dirt but residents must bring and fill their own bags. A new shipment of sandbags is expected Thursday. (Mike Lang/Sarasota Herald-Tribune via AP) MIAMI, FL - SEPTEMBER 06: Storm clouds are seen on the horizon as people throughout South Florida prepare for Hurricane Irma on September 6, 2017 in Miami, Florida. It's still too early to know where the direct impact of the hurricane will take place but the state of Florida is in the area that seems most likely to take a hit. (Joe Raedle/Getty Images) A picture taken on September 7, 2017 shows flooded houses in Gustavia on the French overseas collectivity of Saint-Barthelemy in the Caribbean following hurricane Irma. Hurricane Irma sowed a trail of deadly devastation through the Caribbean, reducing to rubble the tropical islands of Barbuda and St Martin and claiming at least seven lives. / AFP PHOTO / Kevin BarrallonKEVIN BARRALLON/AFP/Getty Images (Kevin Barrallon/AFP/Getty Images) A picture taken on September 7, 2017 shows wreckages in a street of Gustavia on the French overseas collectivity of Saint-Barthelemy in the Caribbean following hurricane Irma. Hurricane Irma sowed a trail of deadly devastation through the Caribbean, reducing to rubble the tropical islands of Barbuda and St Martin and claiming at least seven lives. / AFP PHOTO / Kevin BarrallonKEVIN BARRALLON/AFP/Getty Images (Kevin Barrallon/AFP/Getty Images) A picture taken on September 7, 2017 shows a flooded street in Gustavia on the French overseas collectivity of Saint-Barthelemy in the Caribbean following hurricane Irma. Hurricane Irma sowed a trail of deadly devastation through the Caribbean, reducing to rubble the tropical islands of Barbuda and St Martin and claiming at least seven lives. / AFP PHOTO / Kevin BarrallonKEVIN BARRALLON/AFP/Getty Images (Kevin Barrallon/AFP/Getty Images) Families gather at a shelter in a local church during the evening before the arrival of Hurricane Irma in Las Terrenas, Dominican Republic, Wednesday, Sept. 6, 2017. Dominicans wait for the arrival of Hurricane Irma after it lashed Puerto Rico with heavy rain and powerful winds, leaving nearly 900,000 people without power as authorities struggled to get aid to small Caribbean islands already devastated by the historic storm. (AP Photo/Tatiana Fernandez) A man covers a bodega's windows before the arrival of Hurricane Irma in Las Terrenas, Dominican Republic, Wednesday, Sept. 6, 2017. Dominicans are getting ready for the arrival of Hurricane Irma after battering Puerto Rico with heavy rain and powerful winds, leaving more than 600,000 people without power as authorities struggle to get aid to small Caribbean islands already devastated by the historic storm.(AP Photo/Tatiana Fernandez) High winds and rain sweep through the streets of the Matelnillo community during the passage of hurricane Irma, in Fajardo, Puerto Rico, Wednesday, Sept. 6, 2017. The US territory was first to declare a state of emergency las Monday, as the National Hurricane Center forecast that the storm would strike the Island Wednesday. (AP Photo/Carlos Giusti) This handout picture released on September 6, 2017, on the twitter account of RCI.fm shows a flooded street on the French overseas island of Saint-Martin, after high winds from Hurricane Irma hit the island. Monster Hurricane Irma slammed into Caribbean islands today after making landfall in Barbuda, packing ferocious winds and causing major flooding in low-lying areas. As the rare Category Five storm barreled its way across the Caribbean, it brought gusting winds of up to 185 miles per hour (294 kilometers per hour), weather experts said. / AFP PHOTO / RCI Guadeloupe AND TWITTER / Rinsy XIENG / RESTRICTED TO EDITORIAL USE - MANDATORY CREDIT "AFP PHOTO / RCI .fm / Rinsy XIENG" - NO MARKETING NO ADVERTISING CAMPAIGNS - DISTRIBUTED AS A SERVICE TO CLIENTS --RINSY XIENG/AFP/Getty Images (Rinsy Xieng/AFP/Getty Images) This handout picture released on September 7, 2017, by RCI.fm shows damages on the French overseas island of Saint-Martin, after high winds from Hurricane Irma hit the island. Powerful Hurricane Irma cut a swathe of deadly destruction as it roared through the Caribbean on September 6, 2017, claiming at least nine lives and turning the tropical islands of Barbuda and St Martin into mountains of rubble. / AFP PHOTO / rci.fm / Rinsy XIENG / RESTRICTED TO EDITORIAL USE - MANDATORY CREDIT "AFP PHOTO / RINSY XIENG / RCI.FM" - NO MARKETING NO ADVERTISING CAMPAIGNS - DISTRIBUTED AS A SERVICE TO CLIENTS RINSY XIENG/AFP/Getty Images (Rinsy Xieng/AFP/Getty Images) A picture released on the Facebook account of Kevin Barralon on September 7, 2017 shows a destroyed building in Gustavia on the French overseas collectivity of Saint-Barthelemy in the Caribbean following hurricane Irma. Hurricane Irma sowed a trail of deadly devastation through the Caribbean, reducing to rubble the tropical islands of Barbuda and St Martin and claiming at least seven lives. / AFP PHOTO / FACEBOOK / Kevin Barrallon / RESTRICTED TO EDITORIAL USEKEVIN BARRALLON/AFP/Getty Images (Kevin Barrallon/AFP/Getty Images) epa06189189 A handout photo made available by the Dutch Department of Defense on 07 September 2017 shows an aerial view over the damage of Hurricane Irma in Philipsburg, Sint Maarten, 06 September 2017. Hurrican Irma was declared the most powerful hurricane ever recorded over the Atlantic Ocean, and left a path of destruction in the Caribbean as it approaches Florida. EPA-EFE/Gerben van Es/DUTCH DEPARTMENT OF DEFENSE / HANDOUT HANDOUT EDITORIAL USE ONLY/NO SALES (Gerben Van Es/Dutch Department Of Defense / Handout/Epa-Efe) A man drives through rain and strong winds during the passage of hurricane Irma, in Fajardo, Puerto Rico, Wednesday, Sept. 6, 2017. The US territory was first to declare a state of emergency las Monday, as the National Hurricane Center forecast that the storm would strike the Island Wednesday. (AP Photo/Carlos Giusti) MIAMI BEACH, FL - SEPTEMBER 07: Dr. Steven Gayer walks away with freshly filled sand bags while preparing for approaching Hurricane Irma on September 6, 2016 in Miami Beach, Florida. Current tracks for Hurricane Irma shows that it could hit south Florida this weekend. (Mark Wilson/Getty Images) People walk through damage on September 7, 2017, in a sand-covered street of Marigot, near the Bay of Nettle, on the island of Saint-Martin in the northeast Caribbean, after the passage of Hurricane Irma. France, the Netherlands and Britain on September 7 sent water, emergency rations and rescue teams to their stricken territories in the Caribbean hit by Hurricane Irma, which has killed at least 10 people. The worst-affected island so far is Saint Martin, which is divided between the Netherlands and France, where eight of the 10 confirmed deaths took place. / AFP PHOTO / Lionel CHAMOISEAULIONEL CHAMOISEAU/AFP/Getty Images (Lionel Chamoiseau/AFP/Getty Images) This handout picture released on the Twitter account of Anna Mazur on September 7, 2017 shows the damaged Casino Royale, on the Dutch Caribbean island of Sint Maarten, after the passage of Hurricane Irma. Powerful Hurricane Irma cut a swathe of deadly destruction as it roared through the Caribbean, claiming at least nine lives and turning the tropical islands of St Martin and Barbuda into mountains of rubble. / AFP PHOTO / TWITTER AND AFP PHOTO / Anna MAZUR / RESTRICTED TO EDITORIAL USE - MANDATORY CREDIT "AFP PHOTO / TWITTER / ANNA MAZUR" - NO MARKETING NO ADVERTISING CAMPAIGNS - DISTRIBUTED AS A SERVICE TO CLIENTS ANNA MAZUR/AFP/Getty Images (Anna Mazur/AFP/Getty Images) Winds brought by Hurricane Irma blow palm trees in Samana, Dominican Republic, Thursday, Sept. 7, 2017. Irma cut a path of devastation across the northern Caribbean, leaving thousands homeless after destroying buildings and uprooting trees. Irma is flooding parts of the Dominican Republic as it roars by just off the northern coast of the island it shares with Haiti. (AP Photo/Tatiana Fernandez) Damaged vehicles are seen following Hurricane Irma hitting Sint Maarten, the Dutch side of the Caribbean island of Saint Martin September 7, 2017 in this image taken from social media. Mandatory credit EZE EGWUATU/Handout MANDATORY CREDITvia REUTERS THIS IMAGE HAS BEEN SUPPLIED BY A THIRD PARTY. MANDATORY CREDIT.NO RESALES. NO ARCHIVES (Social Media/Reuters) epa06190109 People look down on a flooded street from a roof in Santiago de los Caballeros, Dominican Republic, 07 September 2017. More than 5,500 people have been evacuated in the Dominican Republic because of the powerful category 5 hurricane Irma, which is causing rains and strong winds in the northeast of the country after leaving Puerto Rico. EPA-EFE/Luis Tavarez (Luis Tavarez/EPA-EFE) epa06190108 A young man walks trough a flooded street in Santiago de los Caballeros, Dominican Republic, 07 September 2017. More than 5,500 people have been evacuated in the Dominican Republic because of the powerful category 5 hurricane Irma, which is causing rains and strong winds in the northeast of the country after leaving Puerto Rico. EPA-EFE/Luis Tavarez (Luis Tavarez/EPA-EFE) Waves crash against a boat near the shore as Hurricane Irma passes over Samana, Dominican Republic, Thursday, Sept. 7, 2017. Hurricane Irma cut a path of devastation across the northern Caribbean. (AP Photo/Tatiana Fernandez) epa06190443 View of wreckage in the vicinity of the Santurce neighborhood in the aftermath of the hurricane Irma, in San Juan, Puerto Rico, 7 September 2017. Puerto Rico's Governor Ricardo Rossello, reported that three people have died in events related to the passage of Hurricane Irma, while the biggest incidents that have been recorded are fallen trees and electric poles. EPA-EFE/Thais Llorca (Thais Llorca/EPA-EFE) An employee works to remove a felled tree from a rooftop in the aftermath of Hurricane Irma, in Fajardo, Puerto Rico, Thursday, Sept. 7, 2017. Irma cut a path of devastation across the northern Caribbean, leaving at least 10 dead and thousands homeless after destroying buildings and uprooting trees. More than 1 million people in Puerto Rico are without power. (AP Photo/Carlos Giusti) Rocks are scattered on a road in the aftermath of Hurricane Irma, in Fajardo, Puerto Rico, Thursday, Sept. 7, 2017. Irma cut a path of devastation across the northern Caribbean, leaving at least 10 dead and thousands homeless after destroying buildings and uprooting trees. More than 1 million people in Puerto Rico are without power. (AP Photo/Carlos Giusti) A woman pulls a travel case on a rock scattered road in the aftermath of Hurricane Irma in Fajardo, Puerto Rico, on September 7, 2017. One of the most powerful Atlantic storms on record, the rare Category 5 hurricane churned westward off the northern coast of Puerto Rico early Thursday on a potential collision course with south Florida, where at-risk areas were evacuated. / AFP PHOTO / Ricardo ARDUENGORICARDO ARDUENGO/AFP/Getty Images (Ricardo Arduengo/AFP/Getty Images) A man looks out to the flooded street as Hurricane Irma moves off the northern coast of the Dominican Republic, in Puerto Plata, Dominican Republic September 7, 2017. REUTERS/Ivan Alvarado (Ivan Alvarado/Reuters) Residents line up at Frost Park in Dania Beach, Fla., and fill up sandbags in preparation of Hurricane Irma in Dania Beach, Fla., on Thursday, Sept. 7, 2017. Irma cut a path of devastation across the northern Caribbean, leaving thousands homeless after destroying buildings and uprooting trees on a track Thursday that could lead to a catastrophic strike on Florida. (Mike Stocker/South Florida Sun-Sentinel via AP) A photo taken on September 6, 2017 shows debris in Marigot, near the Bay of Nettle, on the French Collectivity of Saint Martin, after the passage of Hurricane Irma. France, the Netherlands and Britain on September 7 sent water, emergency rations and rescue teams to their stricken territories in the Caribbean hit by Hurricane Irma, which has killed at least 10 people. The worst-affected island so far is Saint Martin, which is divided between the Netherlands and France, where eight of the 10 confirmed deaths took place. / AFP PHOTO / Lionel CHAMOISEAULIONEL CHAMOISEAU/AFP/Getty Images (Lionel Chamoiseau/AFP/Getty Images) A photo taken on September 6, 2017 shows a damaged building at the Hotel Mercure in Marigot, near the Bay of Nettle, on the French Collectivity of Saint Martin, after the passage of Hurricane Irma. France, the Netherlands and Britain on September 7 sent water, emergency rations and rescue teams to their stricken territories in the Caribbean hit by Hurricane Irma, which has killed at least 10 people. The worst-affected island so far is Saint Martin, which is divided between the Netherlands and France, where eight of the 10 confirmed deaths took place. / AFP PHOTO / Lionel CHAMOISEAULIONEL CHAMOISEAU/AFP/Getty Images (Lionel Chamoiseau/AFP/Getty Images) A photo taken on September 6, 2017 shows a car turned onto its side in Marigot, near the Bay of Nettle, on the French Collectivity of Saint Martin, after the passage of Hurricane Irma. France, the Netherlands and Britain on September 7 sent water, emergency rations and rescue teams to their stricken territories in the Caribbean hit by Hurricane Irma, which has killed at least 10 people. The worst-affected island so far is Saint Martin, which is divided between the Netherlands and France, where eight of the 10 confirmed deaths took place. / AFP PHOTO / Lionel CHAMOISEAULIONEL CHAMOISEAU/AFP/Getty Images (Lionel Chamoiseau/AFP/Getty Images) epa06190263 A handout photo made available by the Dutch Department of Defense on 07 September 2017 shows an aerial view of the damages of Hurricane Irma in Philipsburg, Sint Maarten, 06 September 2017. Hurrican Irma was declared the most powerful hurricane ever recorded over the Atlantic Ocean, and left a path of destruction in the Caribbean as it approaches Florida. EPA-EFE/GERBEN VAN ES / DUTCH DEPARTMENT OF DEFENSE / HANDOUT HANDOUT EDITORIAL USE ONLY/NO SALES (Gerben Van Es / Dutch Department Of Defense / Handout/EPA-EFE) A photo taken on September 7, 2017 shows damage in Orient Bay on the French Carribean island of Saint-Martin, after the passage of Hurricane Irma. France, the Netherlands and Britain on September 7 rushed to provide water, emergency rations and rescue teams to territories in the Caribbean hit by Hurricane Irma, with aid efforts complicated by damage to local airports and harbours. The worst-affected island so far is Saint Martin, which is divided between the Netherlands and France, where French Prime Minister Edouard Philippe confirmed four people were killed and 50 more injured. / AFP PHOTO / Lionel CHAMOISEAULIONEL CHAMOISEAU/AFP/Getty Images (Lionel Chamoiseau/AFP/Getty Images) This Sept. 6, 2017 photo provided by the Dutch Defense Ministry shows a view of St. Maarten, in the aftermath of Hurricane Irma. Irma cut a path of devastation across the northern Caribbean, leaving thousands homeless after destroying buildings and uprooting trees. Significant damage was reported on the island that is split between French and Dutch control. (Gerben Van Es/Dutch Defense Ministry via AP) epa06191556 A handout photo made available by the Dutch Department of Defense on 08 September 2017 shows damage caused by Hurrican Irma in Philipsburg, Sint Maarten, on 07 September 2017. Dutch military and civilian emergency services arrived at the island territory to help after Hurricane Irma was declared the most powerful hurricane ever recorded over the Atlantic Ocean, and left a path of destruction on Sint Maarten and in the Caribbean as it approaches Florida. Sint Maarten is an autonomous country of the Kingdom of the Netherlands on the Carbbean island of Saint Martin. EPA-EFE/GERBEN VAN ES/DUTCH DEPARTMENT OF DEFENSE/HANDOUT HANDOUT EDITORIAL USE ONLY/NO SALES (Gerben Van Es/Dutch Department Of Defense/Handout/EPA-EFE) Lilimar Garcia loads sandbags in her car to prepare for the arrival of Hurricane Irma, Friday, Sept. 8, 2017, in Orlando, Fla. Lines of vehicles stretched for miles and many waited several hours to get the sandbags. (AP Photo/John Raoux) Sand is dumped along the dunes on Route A1A as protection ahead of Hurricane Irma in Flagler Beach, Fla., Friday, Sept. 8, 2017. (AP Photo/David Goldman) MIAMI BEACH, FL - SEPTEMBER 08: A message reading "You Don't Scare Us Irma" is written on plywood being used to cover the windows of a building as people prepare for the arrival of Hurricane Irma on September 8, 2017 in Miami Beach, Florida. Florida appears to be in the path of the Hurricane which may come ashore at category 4. (Joe Raedle/Getty Images) Hotel worker Luisa Perez, 27, takes her belongings to a relative's house prior to the arrival of the Hurricane Irma in Caibarien, Cuba September 8, 2017. REUTERS/Alexandre Meneghini (Alexandre Meneghini/Reuters) epa06192699 A fuel pump is protectively wrapped in plastic ahead of the expected arrival of Hurricane Irma in Key Biscayne, Florida, USA, 08 September 2017. Miami Beach, the Florida Keys and other low-lying areas are under a mandatory evacuation order ahead of Irma. EPA-EFE/ERIK S. LESSER (Erik S. Lesser/EPA-EFE) PUNTA GORDA, FL - SEPTEMBER 08: Traffic on Interstate 75 while moving in both directions, was noticeably heavier in the northbound lanes as residents and visitors in Florida evacuate the area ahead of Hurricane Irma on September 08, 2017 in Punta Gorda, Florida. Florida appears to be in the path of the hurricane which may come ashore at category 4. (Brian Blanco/Getty Images) Hundreds of people gather in an emergency shelter at the Miami-Dade County Fair Expo Center in Miami, Florida, September 8, 2017, ahead of Hurricane Irma. Florida Governor Rick Scott warned that all of the state's 20 million inhabitants should be prepared to evacuate as Hurricane Irma bears down for a direct hit on the southern US state. / AFP PHOTO / SAUL LOEBSAUL LOEB/AFP/Getty Images (Saul Loeb/AFP/Getty Images) Aerial view of devastation following Hurricane Irma at Bitter End in Virgin Gorda, British Virgin Islands September 8, 2017, is seen in this still image taken from social media video. MANDATORY CREDIT Caribbean Buzz Helicopters/via REUTERS THIS IMAGE HAS BEEN SUPPLIED BY A THIRD PARTY. MANDATORY CREDIT. NO RESALES. NO ARCHIVES (Social Media/Reuters) Aerial view of devastation following Hurricane Irma on Saba Rock, British Virgin Islands September 8, 2017, is seen in this still image taken from social media video. MANDATORY CREDIT Caribbean Buzz Helicopters/via REUTERS THIS IMAGE HAS BEEN SUPPLIED BY A THIRD PARTY. MANDATORY CREDIT. NO RESALES. NO ARCHIVES (Social Media/Reuters) A man walks on a street covered in debris after hurricane Irma hurricane passed on the French island of Saint-Martin, near Marigot on September 8, 2017. Officials on the island of Guadeloupe, where French aid efforts are being coordinated, suspended boat crossings to the hardest-hit territories of St Martin and St Barts where 11 people have died. Two days after Hurricane Irma swept over the eastern Caribbean, killing at least 17 people and devastating thousands of homes, some islands braced for a second battering from Hurricane Jose this weekend. / AFP PHOTO / Martin BUREAUMARTIN BUREAU/AFP/Getty Images (Martin Bureau/AFP/Getty Images) KEY LARGO, FL - SEPTEMBER 08: Boats that can't be evacuated are tied off in canals to protect them from Hurricane Irma on September 8, 2017 in Key Largo, Florida. The entire Florida Keys are under a mandatory evacuation notice as Hurricane Irma approaches the low-lying chain of islands south of Miami. (Marc Serota/Getty Images) Miami Beach, FL - SEPTEMBER 08: Mike Bazini works to put hurricane shutters on windows at Playwright Irish Pub before Hurricane Irma hits on Friday September 08, 2017 in Miami Beach, FL. (Matt McClain/The Washington Post) Miami Beach, FL - SEPTEMBER 08: People are seen on the beach before Hurricane Irma hits on Friday September 08, 2017 in Miami Beach, FL. (Matt McClain/The Washington Post) Photo Gallery: Irma is wielding the most powerful winds ever recorded for a storm in the Atlantic Ocean.

“Hurricane Irma’s magnitude compares to no other weather system in the recorded history of Puerto Rico. … We have expended substantial resources in preparation for this disaster and without the assistance of the federal government, the local communities will be unable to recover effectively,” Ricardo Rosselló Nevares wrote in the letter.

On Tuesday evening, President Trump declared emergencies in Florida, the U.S. Virgin Islands and Puerto Rico due to Irma.

Computer models show the storm approaching the Florida Keys by the weekend and then turning sharply northward. Its path beyond that is more uncertain, with models showing that it could then track up either the west coast of Florida or the East Coast of the United States, or climb up the center of the peninsula. The storm could also churn into the Gulf of Mexico. But the hurricane’s size suggests that its effects could be felt far from its center — perhaps as far as 200 miles out — forecasters say.

In Key West on Tuesday afternoon, residents and tourists were on high alert, with officials already issuing an evacuation for all visitors beginning Wednesday morning. Hotels here are closing down, many businesses on Key West’s famed Duval Street were shuttered — with the exception of a few bars and restaurants — and many residents were streaming to the mainland by car on Route A1A.

Carolyn Boutte, 44, said she and her husband moved to a house in Key West four years ago from Gloucester, Mass., and they have never been through a hurricane threat like this. They were searching for gas on Tuesday so they could escape, but the first three stations already had run out of fuel and lines were long everywhere else. She finally ran into some luck — at a station where she had to wait 45 minutes for a fill.

“My husband and I are packing up the dog and our Harley Davidson,” said Boutte, a marine biologist. “Unless the hurricane changes paths, we are getting out of here in the next couple of days.”

Hurricane Irma promised to test once again the Trump administration’s ability to respond to a major natural disaster, just days after Hurricane Harvey pummeled Texas, leaving record damage in its wake. William “Brock” Long, administrator of the Federal Emergency Management Agency, said that incident management assistance personnel already are on the ground in vulnerable areas.

“Just like in Texas, the response to Irma is going to take all levels of government and the whole community,” Long said in a statement. “This has the potential to be a catastrophic storm.”

That potential appeared to be sinking in particularly in the Florida Keys, where gas stations reported low fuel stocks and grocery stores ran out of bottled water. Residents and business owners boarded up windows and hauled boats out of the water. Tourists and residents had already begun crowding up the single highway that snakes through the 120-mile island chain and into the Florida mainland.

Some planned to ride out the storm, despite the dire warnings. Monroe County commissioner Sylvia Murphy, who has lived on the Florida Keys since 1954, said she and a few guests would hunker down in her home, which sits about 12 feet above sea level atop the ridge that runs along the islands. Her house has a new metal roof, she said, and is surrounded by trees, which help block the wind gusts.

“The water won’t get me,” she said by phone Tuesday.

Others in the state, meanwhile, planned to play it safe.

School districts in the large counties of southern Florida all announced they were canceling classes later this week, including Broward, Miami-Dade and Palm Beach, three of the nation’s largest with a combined enrollment of more than 800,000 students. The NFL said the Miami Dolphins season opener scheduled for Sunday afternoon would not be played in South Florida as planned, and would move either to a neutral location the same day or would be rescheduled for later in the season.

Florida Gov. Rick Scott (R), who has declared a statewide emergency, wrote to Trump on Tuesday asking him to declare a pre-landfall emergency in Florida, warning that Irma could require large-scale evacuations. He has activated 100 members of the Florida National Guard and said he has directed all 7,000 members to report for duty on Friday.

Scott ordered Florida transportation officials to suspend tolls across the state as of 5 p.m. Tuesday, which could help lessen congestion on the crowded arteries drivers will use to escape the storm’s potential path.

The uncertainty of Irma’s track and the geography of the Florida peninsula have combined to create an unusually broad, essentially statewide sense of emergency. Most of Florida’s population lives close to the coast, and Irma could potentially ride up either side or track further west into the Gulf of Mexico and endanger the state’s panhandle.

In Estero, on the state’s Gulf Coast, residents were either hunkering down or starting to flee. Stocks of water and flashlights at grocery stores were wiped out, and gas was becoming scarce. A sign on the door of a Speedway gas station warned customers: “No gas, no propane, no water, sorry.”

“We’ve never been this worried in our entire lives,” said Jose Torres, 25, who plans to evacuate to Georgia on Wednesday.

South Florida’s three big counties — Dade, Broward and Palm Beach — last year surpassed 6 million in population for the first time, and routes out of the area are impeded by the Everglades and vast swamps just inland of the inhabited regions. The main routes north are Interstate 95 and the Florida Turnpike. The main route west is Interstate 75 — the so-called “Alligator Alley” — but that takes South Florida’s residents to the imperiled southwest coast of the state. If the storm does track up the state’s spine, as Scott noted, that could make evacuations extremely complex.

The last major hurricane — registering as a Category 3 storm or stronger — to make landfall in Florida was Hurricane Wilma in October 2005. Wilma also was the last major hurricane to make landfall in the United States until Harvey struck Texas late last month.

While the hurricane center said Irma’s intensity could fluctuate, it is expected to remain a Category 4 or 5 storm during coming days. The hurricane center was blunt about Irma’s potential impact, calling the storm “extremely dangerous” and “potentially catastrophic.”

“Everyone should continue to monitor, check supplies, and be ready to implement action plan,” the National Weather Service in Miami posted Tuesday morning on Twitter.

The University of Miami said Tuesday it was canceling classes beginning on Wednesday and through the end of the week at two of its campuses, including its main property in Coral Gables, south of downtown Miami.

Miami city officials urged residents who live in buildings next to construction cranes to evacuate in advance of the hurricane, saying that the cranes are designed to withstand winds up to 145 miles per hour, not a Category 5 storm. “The arm’s counterbalance is very heavy and poses a potential danger if the crane collapses,” the city said in a statement, noting that the danger is greatest for people living in high-rises.

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The warnings in Florida arrive not long after the state marked the 25th anniversary of Hurricane Andrew’s devastating landfall there, and as residents — like many others nationwide — have spent recent days glued to news reports documenting Harvey’s mammoth impact in Texas.

If Irma does make landfall as a Category 4 storm or stronger so close after Harvey’s impact on the Gulf Coast, it will be the first time on record that two Atlantic storms of that strength hit the United States during the same hurricane season.

Somashekhar and Berman reported from Washington. Janine Zeitlin in Estero, Fla.; and Joel Achenbach, Moriah Balingit, Angela Fritz and Jason Samenow in Washington contributed to this story, which has been updated since it was first published at 8:47 a.m.