Hurricane Irma surged to a dangerous Category Four storm Monday as it churned toward the Leeward islands, sparking alarm and alerts from the Caribbean to Florida, which declared an emergency.

The National Hurricane Center said at 2100 GMT that the storm was packing top sustained winds of 130 mph (215 km/h). "Additional strengthening is forecast during the next 48 hours," the NHC warned.

"On the forecast track, the center of Irma will move near or over portions of the northern Leeward Islands Tuesday night and early Wednesday