Boat torn from its moorings by Hurricane Irene
Hurricane Irene howled ashore in North Carolina with heavy winds and waves unmooring a sailboat in Morehead City, in North Carolina.
The heavy rains have also flooded some streets in the port city.
With winds of 85 miles per hour, Irene had weakened to a Category 1 hurricane on the five-step Saffir-Simpson intensity scale, but forecasters and officials warned that it remained large and dangerous.
Some 370,000 city residents are under orders to leave their homes in low-lying areas, many of them in parts of the boroughs of Brooklyn and Queens and in downtown Manhattan.
New York's mass transit system, which carries 8.5 million people on weekdays, was to shut down at around midday on Saturday.
The eye of the storm crossed the North Carolina coast near Cape Lookout around 7:30am (1130 GMT), forecasters at the US National Hurricane Centre said.
Irene was moving north-northeast along the coast and was expected to remain a hurricane as it hit the mid-Atlantic states on Saturday night and New England on Sunday.
Irene was the first hurricane to hit the US mainland since Ike pounded Texas in 2008.
Flooding from Irene killed at least one person in Puerto Rico and two in the Dominican Republic.