Roman Alvarez (L) and Bob Alvarez use plywood to secure...

Roman Alvarez (L) and Bob Alvarez use plywood to secure a business against the winds of Hurricane Irene on August 27, 2011 in Southhampton, New York. Credit: Getty Images

Long Islanders by the thousands were evacuating Saturday, a day after county and town officials ordered mandatory evacuations for nearly 400,000 people, declaring states of emergency two days before Hurricane Irene is scheduled to strike.

In Nassau, County Executive Edward Mangano called for the evacuation of all residents in areas south of some stretches of Sunrise Highway and Merrick Road as well as low-lying North Shore areas. Nassau's order potentially affects 300,000 people.

In Suffolk, Brookhaven's evacuation begins Saturday at 8 a.m. for low-lying areas, defined as 10 feet or less above sea level, on the South Shore, which includes parts of Blue Point, Patchogue and Bellport, to name a few. The move affects about 70,000 people, officials said.

Islip Supervisor Phil Nolan joined Brookhaven Supervisor Mark Lesko in calling for mandatory evacuations. Islip's order affects an estimated 15,200 residents in low-lying hamlet areas south of Montauk Highway.

Gov. Andrew M. Cuomo said Friday that barrier island residents should evacuate immediately. "This is a very serious situation," he said during a conference call with Nassau officials. "Now is the time to do this."

Suffolk County Executive Steve Levy said 11 shelters will be opened in the county in conjunction with the Red Cross. A Red Cross shelter will be open at 10 a.m. Saturday at Robert Frost Middle School at 450 Half Hollow Rd., Deer Park.

Riverhead Town Supervisor Sean Walter declared a state of emergency effective at 10 a.m. Saturday, and may impose mandatory evacuation in at-risk areas.

Hempstead Town Supervisor Kate Murray and Long Beach City Manager Charles Theofan urged residents to evacuate there before roads become flooded and traffic heavy.

The order to evacuate Fire Island touched off an exodus, with vacationers and year-round residents alike filing onto ferries with packed bags and children.

"I have to leave," said Donna Jordan, 56, of Commack, who arrived at Ocean Beach on Thursday and had planned to stay until Sunday. "I was expecting a weekend of fun and excitement. Guess what? I have to put it in neutral."

Ethan Ganc and Alan Rothenberg said they were nervous after they boarded one of the last ferries back to Fire Island Pines to secure the three-level summer home the Manhattanites bought in 2005. "We've never put up the battens on the windows before," Rothenberg said.

In Nassau and Suffolk counties, residents who planned to stay in their homes were scrambling to prepare for the worst.

Contractor Eddie Perez had a truck full of plywood Friday and was boarding up the fourth of nine Point Lookout houses that he had been hired to secure.

"People are calling like crazy," Perez said. "Hopefully it won't heat up, but if it does, we'll be ready."

Guy Ball, 73, who has lived in the same Point Lookout home since he was 17, had his windows boarded, his appliances unplugged, and his bags packed Friday morning. He and his wife, Mary Lou, were leaving for their daughter's house in Manhasset.

"We've been through storms, but this one sounds like it's going to be the worst," he said. "The rain and stuff you can handle; it's the ocean you worry about," he said.

Denise Bonilla, Robert Brodsky, Sarah Crichton, Ann Givens, Deborah S. Morris, Ann Givens and Kery Murakami

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