Hurricane Irma, which has strengthened again to Category 4, is bearing down on the Florida Keys, bringing damaging winds and heavy rain and leaving at least one person dead.

A man in Monroe County, which encompasses Key West, was killed after he lost control of a truck he has driving that carried a generator as winds whipped at tropical-storm strength, according to the Monroe County Sheriff's Office.

The death toll from the hurricane in the Caribbean meanwhile has risen to 22, bringing the total number of killed to at least 23.

The storm's eye was as of 8 a.m. ET about to move over the Florida Keys, as it was about 20 miles from Key West and 110 miles south of Naples, Florida, on the state's west coast.

Wind gusts up to 82 mph were reported in the Keys and up to 68 mph in Miami, according to the National Hurricane Center, reported ABC meteorologist Dan Manzo.

The National Weather Service earlier Sunday morning urged everyone in the Florida Keys to "hunker down," warning, "the worst winds are yet to come."

A tornado watch is also in effect across the area, with two twisters already reported in South Florida.

In Collier County, emergency vehicles were pulled from the roads Sunday morning as heavy wind gusts began blowing in, the county said.

A weather station near Fort Pierce reported a four-hour rainfall total of 10.53 inches between midnight and 5 a.m. The rainfall rate along the east coast of Florida was 3 inches per hour.

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Parts of Tennessee were under a tropical storm watch Sunday morning, which could bring be a significant wind event for Alabama, Georgia, southern Tennessee and South Carolina.

The storm, which had been downgraded to Category 3 after making landfall as a rare Category 5 hurricane in Cuba early Saturday morning, has sent 124,000 people to Red Cross and Red Cross-affiliated shelters, as of Sunday morning. That figure does not include church and ad hoc shelters. More than six million people have been warned to evacuate its path.

PHOTO: Miami Beach has become a virtual ghost town after tourists and residents flee following the mandatory evacuation for the approaching Hurricane Irma, Sept. 7, 2017. (Thibault Monnier/Pacific Coast News) More

PHOTO: Roof damage caused by high winds brought on by Hurricane Irma is shown, Saturday, Sept. 9, 2017, in Sunny Isles Beach, Fla. (AP Photo/Wilfredo Lee) More

Florida Gov. Rick Scott called the storm unprecedented.

"This is a life-threatening situation," Scott said Saturday. "Our state has never seen anything like it."

The governor stressed the dangers of what he called a "deadly, deadly, deadly storm surge."

Powerful rain and wind are pounding right outside of our house. Thunder, lightning, and flooding too. #HurricaneIrma #Irma @CityofWeston pic.twitter.com/cB4v32qGIr — Lisa Steinberg (@GoodHumorGrl) September 10, 2017

FINALLY getting a quick break from the rain in North Miami but folks already seeing flooding as #Irma gets closer @WPLGLocal10 pic.twitter.com/m5b10OOXh1 — Andrew Perez (@PerezLocal10) September 10, 2017

ABC News meteorologists are forecasting storm surges of 10 feet in Tampa and Sarasota, and 10 to 15 feet from Fort Myers to Naples. Somewhat lower storm surges of 3 to 6 feet may occur from Miami to Key Largo.

Winds were already picking up in Florida early Saturday, with gusts between 40 and 60 mph.

Hurricane-force winds with gusts over 115 mph are possible in the Keys by daybreak Sunday.

Power outages, halted flights and empty ATMs

PHOTO: Waves crash against the Southernmost Point in Key West, Fla., Saturday, Sept. 9, 2017. Hurricane Irma's leading edge bent palm trees and spit rain as the storm swirled toward Florida on Saturday. (Rob O'Neal/The Key West Citizen via AP) More

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