Authorities along the densely populated east coast of the United States have begun mandatory evacuations at popular beach resort areas in preparation for the arrival of the powerful Hurricane Irene.

Irene strengthened and increased in size on Wednesday as it battered the southeastern and central Bahamas with winds as high as 193 kilometers per hour. The storm damaged homes and sent tourists scurrying, but no injuries have been reported.

The National Hurricane Center says Irene could further strengthen to a Category Four storm on a five-point scale by Thursday as it “dangerously approaches” the northwest Bahamas.

The storm is forecast to move up the eastern coast of the U.S. later in the week. The NHC says hurricane and tropical storm watches could be issued for the southeastern coast of the Carolinas by early Thursday.

Irene is the first hurricane to seriously threaten the United States in three years. The Federal Emergency Management Agency says that emergency personnel are preparing all along the coast.

At last report, forecasters said the storm was about 245 kilometers southeast of Nassau, Bahamas, moving northwest at 19 kilometers per hour.

The storm lashed the British territory of the Turks and Caicos Islands Tuesday.

Authorities say Irene could cause flooding in the U.S. mid-Atlantic and New England regions, where soil is saturated from recent heavy rains. They say Irene's tropical storm-force winds extend 410 kilometers from the center.