Hurricane Frances is pounding eastern Florida with drenching rains and fierce winds today, ripping away roofs, trees and boat moorings.
The centre of the storm made landfall at about 6 a.m. Irish time near Sewall's Point, on the Atlantic coast 100 miles north of Miami.
It has led to power cuts for 1.3 million homes and businesses and 2.5 million people have been told to flee after Frances caused large-scale damage to the Bahamas over the previous two days.
Experts say Frances' torrential rain could last for up to 15 hours, in what emergency officials say could be a "marathon" of anxiety and devastation as the storm moved across the state.
Winds reached 105 mph but the slow-moving storm is picking up speed as it moves inland.
In Florida's central Atlantic coast counties, blinding rain squalls drove clouds of sand into the air while huge waves thundered onto the beaches. Palm trees rained coconuts and then toppled over as the eye wall - the most powerful area of the storm surrounding the calm eye - moved ashore.
In hard-hit Palm Beach County, boats broke from their moorings and were dragged by the wind until they snagged on bridges or other obstacles. Power lines snapped and sparked while lightning illuminated blacked-out beach towns and flood waters submerged cars in low-lying parking garages.
The hurricane covered much of the state. Forecasters said the storm's huge eye could take 12 hours to pass, and they warned people not to take false comfort in the respite as the brutal second half of the storm approached.
"People do need to be very careful when those winds do slacken off in the eye. We've still got the back side to deal with," said National Hurricane Center director Mr Max Mayfield.
President Bush has declared the entire state "a major disaster".