GALVESTON, Texas (AP) - Hurricane Rita grew into a monster storm with 170 mph sustained winds as it swirled toward the Gulf Coast, prompting more than 1.3 million residents in Texas and Louisiana to flee in hopes of avoiding a deadly repeat of Katrina.

''It's not worth staying here,'' said Celia Martinez as she and several relatives finished packing up their homes and pets to head to Houston. ''Life is more important than things.''

As Gov. Rick Perry urged residents along the state's entire coast to begin evacuating well in advance of Rita's predicted Saturday landfall, New Orleans braced for the possibility that the storm could swamp the misery-stricken city all over again.

Galveston, Corpus Christi and surrounding Nueces County, low-lying parts of Houston, and New Orleans were under mandatory evacuation orders as Category 5 Rita drew energy from balmy gulf waters.

Galveston Mayor Lyda Ann Thomas told NBC's ''Today'' show Thursday that her city is ''fairly well emptied, but we're sending our police forces … with their loudspeakers reminding people that today is the day to leave.''

In Houston, Mayor Bill White said residents in low-lying areas and in mobile homes should leave immediately.

''We're the best prepared city in the country but nothing of this magnitude is welcome,'' he told ABC's ''Good Morning America.'' ''There's not much you can do if you have 150-mph winds.''