Residents of the Miami area and the Florida Keys streamed north in packed vehicles Friday morning, anxiously rushing to dodge Hurricane Irma as the deadly Category 4 storm took aim at the state's eastern coast after devastating the Caribbean.
The dramatic mass exodus from South Florida could turn into one of the largest evacuations in US history, CNN senior meteorologist Dave Hennen said. Miami-Dade, Broward and Palm Beach counties are home to about 6 million people combined.
Thousands of motorists braved clogged road, backups and slowdowns. Some drivers waited for hours at gas stations, some of which ran out of fuel. The Florida Highway Patrol escorted fuel tankers so they could reach and resupply gas stations, the agency reported.
Travel hot spots included Interstates 95 and 75, and the Florida Turnpike. Troopers monitored roadways, stepping in to help after fender-benders and with disabled cars and trucks.
Mandatory evacuation orders covered parts of Miami-Dade County, Broward County east of US 1, Palm Beach County, low-lying parts of Brevard County, and Monroe County, home to the Florida Keys.
Flying out of the storm zone
Some Floridians unwilling to risk chaos on the highways opted to try to fly out of town. Delta Air Lines added flights out of Miami, Fort Lauderdale and Key West to Atlanta, its largest hub, and allowed passengers affected by Irma to rebook flights for free, the airline said.
American Airlines and United Airlines also waived change fees for passengers impacted by Irma, the airlines said. American planned to wind down operations Friday afternoon at its Miami hub, as well as in other south Florida cities, then to cancel flights throughout the weekend, the airline said.
Irma's impending landfall had forced airlines serving some of the nation's largest airports to plan to shut down operations. By late Saturday, Miami, Orlando and Fort Lauderdale -- home to the 12th, 13th and 21st largest airports in the US, respectively -- were expected to be largely dormant.
The scramble to leave Miami was so acute Thursday evening that air traffic controllers increased the space between flights from Miami and nearby Fort Lauderdale to enable them to better manage the crowded skies, the Federal Aviation Administration said.
Get out now, governor warns
People should get out now, Gov. Rick Scott warned at a Thursday news conference. If they wait until Saturday or Sunday, when high winds and rain are expected to lash South Florida, it will be too late.
"We cannot save you when the storm starts," Scott said. "So, if you are in an evacuation zone and you need help, you need to tell us now."
The National Hurricane Center issued hurricane and storm surge warnings for South Florida on Thursday night.
"You do not want to leave on Saturday, driving through Florida with tropical storm-force winds," CNN meteorologist Tom Sater said.
Added CNN meteorologist Chad Myers: "This is not a Category 1. This is not one to ride out and say, 'Oh, it's just a blow, we'll be fine.' No. If you're in the Keys, you need to go. This isn't an 'always fine' kind of storm."
'Three lanes of red bumper lights'
Roseanne Lesack, her husband and three children were among the evacuees.
They left Boca Raton on Wednesday and headed to Atlanta to stay with friends, she said. After encountering slow traffic, the family spent the night at a motel in Orlando and continued north Thursday morning, Lesack said.
"What should have been another six- or seven-hour travel experience is coming up on 12 hours," she said Thursday night from her vehicle, about 35 miles south of Atlanta. "It has been slow. Right now, we're going about 20 mph. ... It's just three lanes of red bumper lights."
Last year, the family stayed with friends in Florida to ride out Hurricane Matthew, she said, adding that she was glad they decided not to chance it now.
"Now, there are a lot of people who are really nervous about staying but don't feel like they can get out," Lesack said.
'When you dial 911, you will not get an answer'
In Monroe County, home to the Florida Keys, more than 30,000 people -- less than half the population -- had evacuated by Thursday, Scott said. All hospitals would be closed and ambulances, including air transports, would be gone by Friday morning, County Administrator Roman Gastesi said.
"You might as well leave now, while you have a chance, because when you dial 911, you will not get an answer," he said.
Extremely heavy traffic was reported Thursday, including about 4,000 vehicles per hour on I-75 northbound in Lake City, compared with a norm of 1,000 per hour, the Florida Department of Transportation reported. About 1,800 vehicles per hour traveled on I-75 in Collier County, three times as many as usual. Other roads showed smaller increases.
Though nobody knows exactly where Irma will make landfall, governors in Georgia and South Carolina decided not to take chances. They ordered mandatory evacuations of low-lying coastal areas around Savannah and Charleston.
Other eastern Florida population centers soon could be ordered to evacuate, too, depending on Irma's path. Its eye was due to be near Miami early Sunday.
"Look at the size of this storm," Scott said Thursday. "It is wider than our entire state and could cause major and life-threatening impacts from coast to coast. Regardless of what coast you live on, be prepared to evacuate. Floridians on the west coast cannot be complacent."
Emergency fuel deliveries made
Fuel availability had become a major problem, with only about half of Miami's gas stations open, CNN's Miguel Marquez said. At a Marathon gas station in Miami, a line of cars wrapped around the corner, and two police officers kept drivers in line, with police tape stopping them from skipping ahead. Drivers had to wait at least an hour for fuel.
Florida officials took steps to have more fuel delivered, according to a state news release. Emergency contractors by Thursday had secured 1.5 million gallons of fuel, with about 300,000 more barrels of fuel being unloaded from a ship in Tampa to resupply gas stations. A fuel ship from Mississippi was heading to the Port of Tampa and was due to get a military escort, he said.
Scott also suspending toll collections for the duration of the storm.
Limited evacuation routes
A mass evacuation in Florida relies on two primary highways: I-95 along the east coast and I-75 further west. Those roads, as well as the Florida Turnpike, US-27 and other smaller roads that run north, will be "tremendously" clogged, Sen. Bill Nelson of Florida warned.
"If this monster comes right up the peninsula of Florida, you're gonna have a mass out-migration from the south to the north, and it's gonna clog the roads something tremendously," he said. "Therefore, if you are going to evacuate, once the evacuation order is given, don't wait around."
By Friday morning, Irma's cone of potential landfall included almost the entire state of Florida, meaning residents would not be able to flee to the state's Gulf Coast to avoid its wrath. That left a trek north as the best choice.
Tropical storm-force winds from Irma covered more than 65,000 square miles -- about the area of all of Florida.
Memories of rough evacuations linger
Gridlock on Florida roads harked back to chaotic evacuation attempts ahead of Hurricane Floyd, which aimed for Florida before turning north and weakening in 1999, and Hurricane Rita, which hit near the Texas-Louisiana border in 2005.
As Floyd churned toward Florida's eastern coast, about 3 million people across the state, Georgia, South Carolina and North Carolina tried to leave in what became the largest evacuation effort in US history, according to a 2000 FEMA news release. But many evacuees got stranded in gridlock in what FEMA charitably described as a "frustrating effort."
Similar traffic congestion befell Southeast Texas ahead of Rita. A bus carrying elderly evacuees caught fire and exploded, killing at least 24 people and jamming a major evacuation route. Others died during the evacuation due to heat exhaustion, according to the National Hurricane Center.
When Harvey threatened southeast Texas about two weeks ago, Houston officials opted not to issue mandatory evacuation orders, partly owing to lessons learned from those past problems, they said.
Instead, Houston residents were told to hunker down in their homes. Of course, the city flooded and tens of thousands of people had to be rescued.
But the alternative could have been worse, Houston Mayor Sylvester Turner said.
"You literally cannot put 6.5 million people on the road," he said. "If you think the situation right now is bad, you give an order to evacuate, you are creating a nightmare."