"So now we're in the life protection and life-sustaining mode, making sure we have the tarps down there for the homes, we have water, food, cots, blankets, all those types of things we're going to need," David Paulison, Federal Emergency Management Agency administrator, said in a briefing with White House press secretary Dana Perino aboard Air Force One.

Paulison was traveling to Baton Rouge, La., with President George Bush for an on-site assessment of storm damage.

While some places have been opened to evacuated residents, Paulison cautioned people against returning to their homes until local officials say it's safe.

"(Most) of the areas don't have electricity; some of them don't have water, and there's no infrastructure in place," he said. "So we caution people not to come back in until they're sure that their parish has power, has water, sewer, and all those types of things it takes to survive."

Besides helping Gulf Coast states after Hurricane Gustav, FEMA also is preparing to help Atlantic Coast states that may be affected by Hurricane Hanna.

"(We've) already got our supplies ready to move in," Paulison said. "(We've) got a lot of pre-staged stuff in Atlanta, in Florida, and up in North Carolina. I've moved teams into all of those states already."