NEW ORLEANS (AP) — With Gustav approaching hurricane strength and showing no signs of veering off a track to slam into the Gulf Coast, authorities across the region began laying the groundwork Thursday to get the sick, elderly and poor away from the shoreline.

The first batch of 700 buses that could ferry residents inland were being sent to a staging area near New Orleans, and officials in Mississippi were trying to decide when to move Katrina-battered residents along the coast who were still living in temporary homes, including trailers vulnerable to high wind.

The planning for a potential evacuation is part of a massive outline drafted after Hurricane Katrina slammed ashore three years ago, flooding 80 percent of New Orleans and stranding thousands who couldn’t get out in time. As the region prepared to mark the storm’s anniversary Friday, officials expressed confidence those blueprints made them ready for Gustav.

‘‘There are a lot of things that are different between now and what we faced in 2005 when Katrina came ashore,’’ said U.S. Homeland Security Secretary Michael Chertoff, who was flying to Louisiana to meet with New Orleans Mayor Ray Nagin and Gov. Bobby Jindal. ‘‘We’ve had three years to put together a plan that never existed before.’’

With Gustav still several days away, authorities cautioned that no plans were set in stone, and had not yet called for residents to leave. Projections showed the storm arriving early next week as a Category 3 storm, with winds of 111 mph or greater, anywhere from the Florida Panhandle to eastern Texas. But forecasts are extremely tentative several days out, and the storm could change course and strength.

At a news conference Thursday, Nagin said an evacuation order was likely in the coming days, but he didn’t expect officials to tell people to leave before Saturday. Jindal told a later news conference that residents in areas further south could be told to leave starting Friday.

Should officials order an evacuation, police and firefighters will drive through New Orleans neighborhoods, with bull horns, to alert residents. City officials have said they won’t force people to leave but those who stay will be assuming all risks and responsibilities for their families.

In a conference call between the Federal Emergency Management Agency and state and local officials, Harvey Johnson, FEMA’s deputy administrator, cautioned that officals needed to stick to protocols as the storm unfolded.

‘‘It’s very, very important that we play the way we practiced and trained over the last year and a half,’’ he said. ‘‘There’s a way that we operate. There’s a chain of command. There’s a way that we interact with each other. And we can’t afford to be in a disorganized way as we confront the challenges that we’re going to see here.’’

Governors in Mississippi, Louisiana and Texas pre-declared states of emergency in an attempt to build a foundation for federal assistance. Federal officials said resources and personnel to provide post-storm aid were pouring into the Gulf Coast states from other parts of the country Thursday.

The American Red Cross was checking on shelters, deploying trucks that could deliver food, and shipping cots, blankets and hygiene kits into the region. Meanwhile, New Orleans-ara hospitals stocked up on food, medicine, water and diesel fuel while sending the most fragile patients further inland.

Louisiana’s corrections department planned to start moving 9,000 inmates away from coastal areas Friday and into lockups further north, Jindal said.

Batteries, bottled water, and other storm supplies were selling briskly, and people were filling up at gas stations. National Guard troops were readying in Texas, Louisiana and Mississippi. Hotels in the region reported being booked solid by coastal residents planning ahead.

Many residents found themselves repeating the same things they did in the days before Katrina. The New Orleans Saints were set to play the Miami Dolphins in the team’s final NFL preseason game Thursday night; the Saints played their final game of the 2005 preseason just three days before Katrina. Running back Deuce McAllister, who was planning to shore up his suburban home, found it a little weird to be preparing for a possible storm again.

‘‘It’s out of our hands,’’ said McAllister. ‘‘We’ll just have to wait and see what happens.’’

Amid all the preparations, the city still planned to recognize the anniversary. New Orleans planned to hold a ‘‘symbolic’’ burial service for unidentified Katrina victims and a bell-ringing to mark that storm’s three-year anniversary Friday but canceled the jazz funeral that had been planned to precede the service and a candlelight vigil at Jackson Square.

The city said it is prepared to move 30,000 residents in an evacuation; estimates put the city’s current population between 310,000 to 340,000 people. There were about 454,000 here before Katrina hit. Unlike Katrina, there will be no massive shelter at the Superdome, a plan designed to encourage residents to leave.

Residents who need help — the elderly, disabled, those without their own transportation — would be moved out by buses, bound for shelters in other Louisiana cities, and Amtrak trains headed to Jackson, Miss., officials have said. Others are expected to drive themselves.

Melissa Clark, who lives in neighboring Jefferson Parish, said she’s leaving Friday with her family to stay with friends in Clinton, Miss. Her husband, who works in maintenance at a nearby hospital, will stay behind.

‘‘I’m not taking any chances this time,’’ the 35-year-old mother of three teenagers said as she waited fifth in line at a Wal-Mart gas station Thursday.

Not everyone made the same plans. In Alabama, many tourists and residents were taking a wait-and-see attitude, more focused on the Labor Day weekend ahead.

‘‘We plan to sit in a bar and watch the whole thing,’’ joked Greg Lee, a tourist from Clarksville, Tenn. He was grocery shopping to stock up on beverages and planning to stay through the holiday at their beach house at Fort Morgan.