NEW ORLEANS - Along the Gulf Coast, there was simply no time to even count the dead. Engineers scrambled to plug two broken New Orleans levees and rescuers searched for survivors clinging to both hope and rooftops as the swirling, tea-colored water continued to rise.

The flooding in New Orleans grew worse by the minute Tuesday, prompting Gov. Kathleen Blanco to say that everyone still in the city, now huddled in the Superdome and other rescue centers, needs to leave. She said she wanted the Superdome evacuated within two days, but it was still unclear where the people would go.

"The situation is worsening," Blanco said on ABC's "Good Morning America" on Tuesday. Asked if New Orleans would have to be evacuated, she said, "I don't think we can do anything else right now."

To repair damage to one of the levees holding back Lake Pontchartrain, officials late Tuesday dropped 3,000-pound sandbags from helicopters and hauled dozens of 15-foot concrete barriers into the breach. Maj. Gen. Don Riley of the U.S. Army Corps of Engineers said officials also had a more audacious plan: finding a barge to plug the 400-foot hole.

"The challenge is an engineering nightmare," Blanco said. "The National Guard has been dropping sandbags into it, but it's like dropping it into a black hole."

Riley said it could take close to a month to get all the water out of the city. If the water rises a few feet higher, it could also wipe out the water system for the whole city, said New Orleans' homeland security chief, Terry Ebbert.

The U.S. Navy is sending four ships carrying water and other supplies, while medical disaster teams and Red Cross workers from across the country converged on the devastated Gulf Coast region. The Red Cross reported it had about 40,000 people in 200 shelters across the area.

A helicopter view of the devastation over Louisiana and Mississippi revealed people standing on black rooftops baking in the sunshine while waiting for rescue boats.

"I can only imagine that this is what Hiroshima looked like 60 years ago," said Mississippi Gov. Haley Barbour after touring the destruction by air.

All day long, rescuers in boats and helicopters plucked bedraggled flood refugees from rooftops and attics. Louisiana Lt. Gov. Mitch Landrieu said 3,000 people have been rescued by boat and air, some placed shivering and wet into helicopter baskets. They were brought by the truckload into shelters, some in wheelchairs and some carrying babies, with stories of survival and of those who didn't make it.

"Oh my God, it was hell," said Kioka Williams, who had to hack through the ceiling of the beauty shop where she worked as floodwaters rose in New Orleans' low-lying Ninth Ward. "We were screaming, hollering, flashing lights. It was complete chaos."

Looting broke out in some New Orleans neighborhoods, prompting authorities to send more than 70 additional officers and an armed personnel carrier into the city. One police officer was shot in the head by a looter, but was expected to recover, said Sgt. Paul Accardo, a police spokesman.

On New Orleans' Canal Street, dozens of looters ripped open the steel gates on clothing and jewelry stores and grabbed merchandise. In Biloxi, Miss., people picked through casino slot machines for coins and ransacked other businesses. In some cases, the looting was in full view of police and National Guardsmen.Officials said it was simply too early to estimate a death toll. One Mississippi county alone said it had suffered at least 100 deaths, and officials are "very, very worried that this is going to go a lot higher," said Joe Spraggins, civil defense director for Harrison County, home to Biloxi and Gulfport. In neighboring Jackson County, officials said at least 10 deaths were blamed on the storm.Several victims in Harrison County were from a beachfront apartment building that collapsed under a 25-foot wall of water as Hurricane Katrina slammed the Gulf Coast with 145 mph winds Monday. Louisiana officials said many were feared dead there, too, making Katrina one of the most punishing storms to hit the United States in decades.Blanco asked residents to spend today in prayer."That would be the best thing to calm our spirits and thank our Lord that we are survivors," she said. "Slowly, gradually, we will recover; we will survive; we will rebuild."Across Louisiana, Mississippi and Alabama, more than 1 million residents remained without electricity, some without clean drinking water. An untold number who heeded evacuation orders were displaced and 40,000 were in Red Cross shelters, with officials saying it could be weeks, if not months, before most will be able to return.Emergency medical teams from across the country were sent into the region and President Bush cut short his Texas vacation Tuesday to return to Washington to focus on the storm damage.Federal Emergency Management Agency director Mike Brown warned that structural damage to homes, diseases from animal carcasses and chemicals in floodwaters made it unsafe for New Orleans residents to come home anytime soon. The sweltering city of 480,000 had no drinkable water, and the electricity could be out for weeks.The Federal Emergency Management Agency is considering putting people on cruise ships, in tent cities, mobile home parks, and so-called floating dormitories - boats the agency uses to house its own employees.Even the Superdome was no longer safe. The dome, which became a shelter for some 20,000 people, has no air conditioning or electricity. Broken toilets and overflowing garbage cans have made for extremely unsanitary conditions.