Hurricane Irma, the most powerful Atlantic Ocean hurricane in recorded history, made its first landfall in the Caribbean early Wednesday as the Category 5 storm rolled toward a likely strike on the south Florida coast this weekend.

At 8 a.m. ET, Irma was about 15 miles west of St.Martin, packing maximum sustained winds of 185 mph, according to the National Hurricane Center. It was moving toward the west-northwest near 16 mph.

The eye passed over Antigua and Barbuda around 2 a.m. ET. Residents said over local radio that phone lines went down as the eye passed. "May God protect us all," local authorities said.

There were no immediate reports of injuries or deaths. Gaston Browne, the prime minister of Antigua and Barbuda, tweeted the islands may have been spared the worst.

Michel Magras, senator on the small French-speaking island of St.Barts, sent a text describing the "monster that passes over us," reports.

"It is apocalyptic, a lot of damage, a lot of roofs torn off," he texted.

On St. Martin, the half-French, half-Dutch island of around 80,000 people directly in the path of the storm, the roof of the main hospital was ripped off by the relentless winds.

French Interior Minister Gerard Collomb said that government buildings on Saint-Martin had been destroyed, the AFP news agency reported.

"We know that the four most solid buildings on the island have been destroyed which means that more rustic structures have probably been completely or partially destroyed," he told reporters. The island prefect, an official appointed by France, and 23 staff took shelter in a concrete-lined room.

The National Hurricane Center said Irma was maintaining sustained winds near 185 mph as it lashed the Leeward Islands with exceptionally strong winds and heavy rain and was heading west-northwest on a path toward Puerto Rico, the Dominican Republic, Haiti and Cuba. It could reach Florida as early as Friday.

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Previous hurricanes with Irma's ferocity such as Hurricane Wilma (2005) and Hurricane Mitch (1998) reached their maximum intensity in either the Gulf of Mexico or the Caribbean Sea. As of 5 a.m. ET, Irma was traveling west-northwest at about 16 mph.

"The chance of direct impacts from Irma beginning later this week and this weekend from wind, storm surge, and rainfall continues to increase in the Florida Keys and portions of the Florida Peninsula," the HRC said. "However, it is too soon to specify the timing and magnitude of these impacts."

A mandatory evacuation for visitors to the Florida Keys began at sunrise Wednesday, with residents required to evacuate later in the day. President Trump has already declared emergencies in Florida, Puerto Rico and the U.S. Virgin Islands, and authorities in the Bahamas said they would evacuate six southern islands.

The U.S. Coast Guard strongly urged mariners to leave the Port of Key West, noting that it is safest when it has a minimum number of vessels. The Coast Guard ordered all oceangoing vessels and barges to head out to sea ahead of the onset of gale force winds.

It's been 25 years since a Category 5 hurricane struck the U.S., and Irma could potentially become just the fourth storm of that strength to barrel into the U.S. Category 5 hurricanes destroy a high percentage of homes, often causing total roof failure and wall collapses. Fallen trees and power poles isolate residential areas. Power outages last for weeks or months. And areas can be uninhabitable for the same time frame.

"Watching Hurricane closely. My team, which has done, and is doing, such a good job in Texas, is already in Florida. No rest for the weary!," Trump tweeted Wednesday.