Hurricane Irma has "blown the roofs" off of buildings, caused flooding and cut communications between Paris and the French-run islands of Saint Barthelemy and Saint Martin, Annick Girardin, French Overseas Territories minister said on Wednesday. 
The hurricane made landfall just before 06:00 GMT in Barbuda, part of the twin island nation of Antigua and Barbuda.
Garfield Burford, director of news at government-owned broadcaster ABS TV in Antigua and Barbuda, said that the country has been spared the worse from the "ferocious storm" as emergency services assess damages. 
"It was quite a bit of an experience overnight for us, but all things considered Antigua and Barbuda missed a bullet," he said from Antigua's capital, St. John. "It could've been much worse." 
Burford added: "There have been a few minor injuries that were treated at the hospital but thankfully, no deaths or serious injuries and that itself is a mricale when you consider the ferocity of the storm."
The French weather office said Irma was "a historic hurricane (with) an unprecedented intensity over the Atlantic." 
With the islands on maximum alert ahead of the arrival of the strongest storm ever recorded in the Atlantic, France had raised the alarm over the fate of some 7,000 people who refused to seek shelter. 
"People don't know phenomena of this scale in this part of the Caribbean," Girardin said.
Hurricane Irma carries the potential for coastal storm surges of up to six metres above normal tide levels, the Miami-based National Hurricane Centre said on Wednesday.
The National Weather Service said Puerto Rico had not seen a hurricane of Irma's magnitude since Hurricane San Felipe in 1928, which killed a total of 2,748 people in Guadeloupe, Puerto Rico and Florida.
Warm water is fuel for hurricanes and Irma is over water that is 1C warmer than normal.
The 26C water that hurricanes need goes about 80 metres deep, Jeff Masters, meteorology director of the private forecasting service Weather Underground, told The Associated Press agency.
Its forecast late on Tuesday was for the winds to fluctuate slightly but for the storm to remain at Category Four or Five strength for the next day or two.