GALVESTON, Texas (AP) - As many as 1 million people were ordered to clear out along the Gulf Coast, and hospital and nursing home patients were evacuated yesterday as Hurricane Rita turned into a Category-5, 165-mph monster that could slam Texas by the weekend and inflict more misery on New Orleans.

Forecasters said Rita could be the most intense hurricane on record ever to hit Texas, and easily one of the most powerful ever to plow into the U.S. mainland.

Category 5 is the highest on the scale, and only three Category 5 hurricanes are known to have hit the U.S. mainland - most recently, Andrew, which smashed South Florida in 1992.

All of Galveston, low-lying sections of Houston and Corpus Christi, and a mostly emptied-out New Orleans were under mandatory evacuation orders, one day after Rita sideswiped the Florida Keys as a far weaker storm and caused minor damage.

Having seen what Hurricane Katrina - a Category-4, 145-mph storm - did three weeks ago, many people were taking no chances as Rita swirled across the Gulf of Mexico.

"After this killer in New Orleans, Katrina, I just cannot fathom staying," 59-year-old Ldyyan Jean Jocque said before sunrise as she waited for an evacuation bus outside the Galveston Community Center. She had packed her Bible, some music and clothes into plastic bags and loaded her dog into a pet carrier.

"I really think it is going to be bad. That's really why I'm running. All these years I've stayed here, but I've got to go this time," said 65-year-old Barbara Anders. "I don't have but one life, and it is time for me to go."

The federal government was eager to show it, too, had learned its lesson after being criticized for its sluggish response to Katrina.

It rushed hundreds of truckloads of water, ice and ready-made meals to the Gulf Coast and put rescue and medical teams on standby.