Shopkeepers sandbagged galleries and stores in the French Quarter of the vulnerable Gulf Coast city of New Orleans and workers boarded up city hall as Hurricane Katrina churned across Gulf waters.

Officials in the low-lying city famed for its Mardi Gras parades urged residents to evacuate and stranded tourists to shelter on at least the third floor of their hotels as Katrina threatened to make a second and possibly more deadly assault on the US coast after killing seven people in Florida.

?I think there is a very good possibility it will indeed get stronger?, Max Mayfield, director of the US National Hurricane Center, told WSVN television in Miami. ?This hurricane has the potential to cause extreme damage and large loss of lives if they don?t take action very soon.?

By 0300 GMT on Saturday, Katrina was about 335 miles south-southeast of the mouth of the Mississippi River with 115 mph (190 kph) winds. It had begun a turn to the northwest that could see it roaring ashore somewhere between the Florida-Alabama border and Morgan City in Louisiana today, and taking a course through the heart of US Gulf of Mexico oil and gas production.

Computer models showed that New Orleans, much of which lies below sea level, could be in the storm?s bull?s eye. They also indicated Katrina could grow into at least a Category 4 hurricane on the five-step Saffir-Simpson scale with destructive winds of more than 131 mph (210 kph).

Some predictions saw it becoming a catastrophic Category 5 ? like Hurricane Andrew which struck south of Miami in 1992 and ranks as the costliest natural disaster in US history, or Hurricane Camille in 1969, which just missed New Orleans but devastated Louisiana and Alabama and killed more than 400. New Orleans officials turned some major routes out of the city into one-way streets, helping to speed the exodus.

The Louisiana Superdome would be used to shelter for people with special needs. President Bush declared an emergency in Louisiana, a measure that allows federal emergency assistance. The storm was larger and more powerful than when it hit Florida?s coast on Thursday, killing seven.

Michael Depp Russell McCulley