Authorities in New Orleans have ordered residents to flee, as Hurricane Katrina strengthens into a top-category storm. Katrina could roar ashore between the Florida-Alabama border and Louisiana on Monday. Low-lying New Orleans risks being in the eye of the storm.Its people had been preparing for a battering, although not the mandatory evacuation order that has been issued. A state of emergency has been declared in the city. Katrina has grown into a Category Five hurricane. Since records began, only three such storms have hit the United States. Katrina has already claimed at least seven lives in Florida. The consequences in New Orleans could be much more catastrophic. The last Category Five hurricane to strike the area was Hurricane Camille in 1969 which came ashore in Mississippi – killing over 250 people.