Miami, September 11 (RHC)-- At least four people have died and nearly six million people are without power in Florida, after Hurricane Irma made landfall on Sunday on the Florida Keys as a Category 4 hurricane. The storm also flooded the streets of downtown Miami, turning the city’s main strip, Brickell Avenue, into a three-foot-high raging river.

The storm's arrival sparked one of the largest mass evacuations in U.S. history, with nearly seven million people ordered to leave their homes.

Before hitting Florida, Irma caused widespread devastation across the Caribbean, killing at least 27 people and leveling nearly 90 percent of all structures on Saint Martin and Barbuda. It also displaced more than 100,000 Haitians and destroyed crops in the north of the country.

Cuba has dispatched more than 750 health workers to Caribbean nations to help assist in the aftermath of the most powerful storm ever recorded over the Atlantic Ocean.

Irma, now downgraded to a Category 1 storm, is still barreling across more of Florida and then on to Georgia, Alabama and Mississippi.