Now a Category 3, Hurricane Irma barrels toward Naples

With maximum sustained winds of 120 mph, Hurricane Irma has been downgraded to Category 3, the National Weather Service has said.

The National Weather Service further said that Naples and Marco Island are set to endure some of the strongest winds in the next few hours, adding that the "storm surges that threaten to swallow Florida's coastal cities" could be more dangerous than the winds.

"There is imminent danger of life-threatening storm surge flooding along much of the Florida west coast, including the Florida Keys, where a storm surge warning is in effect," CNN quoted the hurricane center.

"The threat of catastrophic storm surge flooding is highest along the southwest coast of Florida, where 10 to 15 feet of inundation above ground level is expected. This is a life-threatening situation."

Category-4 Hurricane Irma began its assault on Florida, the south-easternmost U.S. state earlier on Sunday, with the storm's northern eyewall reaching the lower Florida Keys on Sunday after making landfall in Cuba.

More than 560,000 residents across 19 counties in south and central Florida are without power, according to Florida Power and Light Department.

Irma lashed the area with forceful winds near 130 miles per hour and the U.S. National Hurricane Centre said it was expected to remain a powerful storm as it moved through the Florida Keys and near the state's west coast, CNN reported.

Keeping an eye on Irma, South Carolina Governor Henry McMaster has issued a mandatory evacuation for some barrier islands, while Georgia Governor Nathan Deal expanded a state of emergency to include 94 counties.

As many as 5.6 million people were evacuated from Florida on Friday to deal with the life-threatening Hurricane Irma.

A few records that Irma has broken are:

-Irma is the strongest Atlantic basin hurricane ever recorded outside the Gulf of Mexico and the Caribbean Sea

-It spent three days as a Category 5 hurricane, the longest Category 5 hurricane since satellite storm-tracking began

-It prompted the largest evacuation in the history of the Bahamas

The National Weather Service say that damaging winds are moving into areas including Key Biscayne, Coral Gables and South Miami.

Florida Gov. Rick Scott (R) activated the Florida National Guard on Tuesday in anticipation of the hurricane. About 4,000 troops were activated on Friday, and Scott said he expected the entire force of more than 8,000 would eventually be called into duty.

Puerto Rico, meanwhile, activated its 5,200 National Guard troops, while the U.S. Virgin Islands activated its nearly 700-member unit for assistance , according to the Pentagon.

United States President Donald Trump's homeland security adviser Tom Bossert said Friday he had spoken to Pentagon and State Department officials and insisted they were prepared to tackle Irma response efforts quickly.