President Bush declared a state of emergency in Louisiana (search) on Saturday because of the approach of Hurricane Katrina (search) and his spokesman urged residents along the coast to heed authorities' advice to evacuate.

Bush, vacationing at his ranch, was being regularly updated about the storm, which is expected to hit land early Monday, White House spokesman Scott McClellan said.

Officials from the Federal Emergency Management Agency (search) continue to coordinate with state authorities in Florida, Mississippi, Louisiana and Alabama, and have prepositioned supplies in areas expected to be affected, he said.

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The president's emergency declaration authorizes the FEMA to coordinate all disaster relief efforts and to provide appropriate assistance in a number of Louisiana parishes, or counties.

Authorities told residents of low-lying coastal communities to head for higher ground. The storm was expected to strengthen as it crosses the Gulf of Mexico and could become a Category 4 hurricane with wind of at least 131 mph.

"We urge residents in the areas that could be impacted to follow the recommendations of local authorities," McClellan said.