The National Hurricane Center downgraded Hurricane Irma to a Category 4 storm Friday, but it is still extremely powerful and a hurricane watch was also issued for a swath of Florida as Irma continued its devastating march across the Caribbean, blasting 155 mph winds and leaving a trail of destruction in its wake.

The storm has already been blamed for at least 11 deaths in the Caribbean. Governors of four Southeast states declared states of emergency. Mandatory evacuations took place in the Florida Keys and are underway in the Miami area.

More: Hurricane Irma churns through Caribbean on way to Florida

More: While Irma takes aim on Florida, Hurricanes Jose and Katia are also threatening 

Here is what we know:

Where is Hurricane Irma now?

As of early Friday, the storm was located near the Turks and Caicos Islands about 500 miles southeast of Miami.

Where is Hurricane Irma heading?

Irma should be near the central Bahamas by later Friday. It was moving to the west-northwest at about 16 mph.

What part of Florida is under the watch?

It’s a pretty large section of South Florida, extending from Jupiter Inlet southward around the Florida peninsula to Bonita Beach, including the Florida Keys, Lake Okeechobee and Florida Bay. Look for the area to expand as Irma draws closer.

Will Hurricane Irma hit Florida?

It sure looks that way. The path the storm will take as it rolls up Florida remains unclear. The Florida Keys are poised to get slammed. Some models show the storm’s eye bending a bit, just to the east of the Florida coast, while other models take the storm right over Miami Beach. It’s just too soon to say.

When will Hurricane Irma hit Florida?

Most models have lrma making landfall in Florida sometime Sunday, but wind and water will be blasting the state before that. And Irma is forecast to remain strong as it heads north, so it’s unclear how far up state the storm’s power will be felt.

How strong will Irma be when it hits?

The hurricane center said Irma’s maximum sustained winds have decreased to near 155 mph. The hurricane center said some fluctuations in strength are likely over the next day or two but Irma is expected to stay a Category 4 storm.

What is the biggest concern from the storm?

A fast-moving storm means the region could avoid the unrelenting rains that Harvey brought to Texas. Florida Gov. Rick Scott, who announced the closing of all state schools, colleges and universities through Monday, warned state residents Thursday that even if their town is spared the brunt of Irma’s wind and rain, there are other dangers. “My biggest concern is the amount of storm surge this storm will bring,” Scott said from the state Emergency Operations Center in Tallahassee. “This can kill you.”

More than 500,000 face evacuation orders

Florida, Georgia, South Carolina and North Carolina declared states of emergency ahead of the storm. In Florida alone, more than 500,000 people are under mandatory evacaution orders. The Florida Keys, Miami Beach, downtown Miami and parts of Broward County, home to Fort Lauderdale, were among areas under mandatory evacuation orders. In Georgia, Gov. Nathan Deal ordered evacuations along the coast.

Evacuees facing unprecedented challenges

Hurricanes in Florida usually hit from the east or west, allowing residents to flee north or south to avoid the damage. But with Irma projected to make an unusual landfall from the south, the Category 4 behemoth could envelop the entire Florida peninsula. That has forced evacuees to drive farther and farther north. Florida Gov. Rick Scott said his office is working with gas suppliers to ensure that gas stations along the Florida Turnpike and I-95 — the main highways leading out of Miami — are kept open and stocked.

What are the airlines doing to prepare?

Several airlines capped fares out of Florida after social media complaints about fare gouging. But they also were winding down some operations as Hurricane Irma tracked closer to several of the state’s busiest airports.

How bad could the damage be in Florida?

Florida has seen Category 5 hurricanes before. Hurricane Andrew roared into South Florida 25 years ago, a fast-moving storm that flattened neighborhoods, tossed cars and trucks around like Matchbox toys, and left millions without power. The storm destroyed more than 25,000 homes and damaged 100,000 others. An Andrew-like storm hitting downtown Miami could cause $300 billion in damage, according to one insurance underwriter.

How much damage has Irma caused already?

After Irma struck Barbuda, its prime minister called the island “barely habitable” and St. Martin, an island split between French and Dutch control, saw extensive damage and was almost completely destroyed in places. In the U.S. Virgin Islands, Irma tore off roofs and crippled the only hospital on St. Thomas. The British government said thet British Virgin Islands needs extensive humanitarian assistance. Destruction in Puerto Rico and Haiti does not appear to be as bad as feared.

Should I be worried about Hurricane Jose?

Over the weekend, Category 3 storm Jose could actually slam into some of the same Caribbean islands that were flattened by Irma just a few days ago. A hurricane watch has been posted for Antigua and Barbuda, parts of which sustained catastrophic damage from Irma. Torrential rainfall could produce “life-threatening flooding” by Saturday across both islands. The British Virgin Islands are also in Jose’s path.

What should I do about my pet?

The American Veterinary Medical Association is reminding pet owners developing disaster plans to include pet evacuation kits. The list is extensive. Important components include 3-7 days worth of food, a two-week supply of medicine, 7 days of water, a dish and water bowl, flea and tick prevention, ownership documents and some “comfort” toys. The Shelter Medicine Program at the University of Florida, part of the state’s disaster response system,says are many pet-friendly shelters that allow the whole family to stay together. “Do not leave your pet behind,” the program urges. “If it’s not safe for you, it’s not safe for your pet.”

What was the strongest storm to hit U.S.?

The strongest storm ever to make landfall in the U.S. hit on Sept. 2, 1935. Hurricanes were not officially named back then, but this one became known as the Florida Keys or Labor Day hurricane because of where and when it hit. The hurricane slammed across South Florida with sustained winds of 185 mph, killing 423 people. Awful as that storm was, perhaps the most horrific storm came 35 years earlier, flattening Galveston, Texas, and killing an estimated 6,000 to 8,000 people.

Contributing: Alan Gomez and Doyle Rice