Emergency workers in the northeastern United States have begun airlifting food and water to thousands of residents stranded by floodwaters from Hurricane Irene.

Authorities said Tuesday that at least a dozen communities in the state of Vermont were unreachable by vehicle because of damage to roads and bridges caused by the state's worst floods in nearly a century. The state was among the worst affected by flooding because of already wet soil.

Further south, in the state of New Jersey, emergency workers rescued more than 500 people from flooded homes, some by boat and others by truck.

Utilities companies said Tuesday three million residents along the East Coast are still without electricity, three days after the storm passed over the most densely populated region of the U.S.

Irene has so far been blamed for at least 43 deaths in the continental U.S. and five deaths in the Caribbean.

Meanwhile, the National Hurricane Center says Tropical Storm Katia in the Atlantic is expected to strengthen into a hurricane Wednesday, possibly becoming a major “Category 3” storm on a 5-point scale by Sunday. Forecasters say it is too early to tell where or if Katia will make landfall.