Irma: Three killed in Florida become hurricane's first victims on US mainland as storm makes landfall

More than 600,000 people have already lost power

At least three people are reported to have been killed as Hurricane Irma sweeps into Florida, carrying 130mph winds and threatening to devastate large parts of the so-called Sunshine State.

As the historic, category-4 storm made landfall and where millions have been evacuated as 130mph winds left almost 600,000 without power, reports said a man in Monroe County, which covers Key West, was killed after he lost control of a vehicle he was in as winds whipped at tropical-storm strength.

ABC News said the man was carrying a generator in anticipation of being without power for some time when the accident happened.

Later, it was reported that two people had died in a head-on crash in Hardee County, southeast of the city of Tampa.

The Florida Highway Patrol spokesman Greg Bueno said the crash happened on Sunday morning, though it was not clear what role the weather may have played. He said police were investigating the crash and no further details were immediately available, according to the Associated Press.

The hurricane made landfall in the US at Cudjoe Key in the lower Florida Keys at 9.10am with top sustained winds of up to 130mph, according to the US National Hurricane Centre in Miami. A gust of 106mph was reported on Big Pine Key.

As the storm followed forecasters predictions and shifted westwards, experts said its path posed a severe threat to the state’s west coast and the Florida Keys.

“This is a worst case scenario for Monroe County, the Florida Keys and the west coast of Florida,” Brock Long, administrator of the Federal Emergency Management Agency (FEMA), told Fox News.

“Any time you're in that northeast quadrant as the storm is moving forward, that’s where the maximum radius winds are that define the intensity of the storm. That’s where the storm surge is most prevalent and the inland winds are going to be tough.”

The hurricane had previously killed 23 people as it devastated a series of Caribbean islands.