New York authorities have evacuated a quarter of a million residents and ordered complete shut down of the mass transit system in an unprecedented preparations to brave out the Hurricane Irene.The Blackhawk and Chinook helicopters were placed on stand by for a weekend of torrential rain and massive storms.About 250,000 people in low-lying areas of Manhattan, Brooklyn and Queens have been evacuated to safer places.Neighbouring New Jersey ordered evacuation of 750,000 people out of the Cape May area.In another first-of-its-kind decision, the authorities said they will shut down the entire transit system – a total of 468 subway stations, 840 miles of rail tracks, buses and commuter trains. The New York Army and Air National Guard would deploy up to 900 soldiers and airmen and over 100 vehicles to support civil authorities.About 175 extra ambulances and personnel will be deployed in regions expected to be hit the hardest by the storm.