NEW ORLEANS — "If we come across a body floating?" Sgt. Chris Fisher of the Jefferson Parish Sheriff's Office asked.

"Let it go," Maj. Bobby Woods replied, as Fisher and other rescue workers prepared for the day's mission. "Let's first go for life."

With hundreds of New Orleans residents stranded on upper floors and roofs by rising floodwater from Hurricane Katrina, rescue teams from across the country mobilized in the gulf area in the largest relief effort since the Sept. 11, 2001, attacks.

The people who were saved emerged with anguished testimony of the human toll.

A 95-year-old invalid drowned in her house after her daughter said she could not carry her to safety.

"I had to give her mouth to mouth," the daughter, Judy Martin, said after swimming to a neighbor's house and being rescued on thethe roof Tuesday.

"She just said, 'I give up,' " Martin said of her mother, Cecile Dupont Martin, a former teacher.

After being deposited on dry land where the highway emerged from the water and rescuers launched their airboats and other shallow-draft vessels, the daughter dropped to her knees, put her forehead on the pavement and wept.

A truckload of National Guard troops said they had helped rush to the hospital a woman who delivered a baby in the back of a state wildlife and fisheries truck.

A man stepped out of a rescue boat cradling a piglet.

Pauline Stauss, 80, was rescued with a dog and three cats that she was keeping for her daughter.

Kate Guelfo, 83, was the first of five in her flooded house to be rescued. With just one spot available in the rescue boat, her housemates pushed her out the window to safety, agreeing themselves to await later rescue. Guelfo's arm was black and blue, but she was grateful.

Such poignant scenes abounded as New Orleans tried to fathom the scope of the disaster that left vast sections of its residential eastern part under water, in places roof deep.

Natural gas bubbled up from severed lines. Petroleum fires flickered on the water.

Power lines dangled onto the roads, and utility poles teetered, snapped like matchsticks.

"It's worse than I thought it was," said Jim Strickland, a team leader for the Federal Emergency Management Agency.

Battling the waters are hundreds of emergency workers mobilized by FEMA, including the Coast Guard and incident situation teams from Texas, Missouri and Tennessee.

The 70-member groups of firefighters and medical specialists arrive with 18-wheelers and other trucks loaded with generators, chainsaws, tents and dogs that can sniff out the living and the dead.