Despite an order to abandon their homes because of the increasingly toxic floodwaters engulfing this city, a few shellshocked and determined holdouts refused to leave Wednesday as hundreds of rescue workers continued going house to house in huge trucks and flat-bottomed boats to evacuate the remaining survivors of Hurricane Katrina.

Warning residents of the threat posed by deadly bacteria in the dark, oily water and trying to coerce others to leave by threatening to cut off deliveries of water and other provisions, hundreds of rescue workers, many wearing surgical masks and plastic gloves to protect them from the stench and disease, struggled to enforce the evacuation order issued Tuesday by Mayor C. Ray Nagin.

Underscoring the concern of rescue crews, the U.S. Centers for Disease Control and Prevention said that three people have died from suspected bacterial infections caused by dirty water resulting from the storm. In addition, the Environmental Protection Agency released findings from floodwater tests in the city that found levels of lead, E. coli, PCBs and other toxins that "greatly exceeded" the agency's recommended levels for safe contact.

As hundreds of thousands of evacuees settled into shelters across the country, officials announced plans to issue $2,000 debit cards to hurricane victims, allowing them to afford essentials such as food, gas and transportation.

"The concept is to get them some cash in hand that empowers them," Federal Emergency Management Agency Director Michael D. Brown told reporters.

While crews sloshed through the slowly receding floodwaters in search of survivors and to mark the location of the dead, the Army Corps of Engineers reported slow progress in pumping the fetid water out of the city. Only five of the city's 148 drainage pumps were operating, the Army Corps of Engineers said. Engineers set up 34 portable units to help drain the city. Hampering their efforts is the debris choking the floodwaters and periodically clogging the pumps.

The scene in the city remained eerily chaotic, as rescue workers cut through the roofs of houses in search of survivors. They went house to house, spray-painting homes already searched with an orange X. If they found a body, they secured it, recorded its satellite coordinates and painted a circle on the house with black spray paint.

"We're searching for survivors because we can do nothing for the people who are dead," said Sgt. Billy Gomillion of the Louisiana Department of Wildlife and Fisheries Enforcement. "They are gone. I don't mean to be disrespectful -- the dead will be taken care of. I feel bad that the bodies are out there. It's a bad situation. But we have to take care of the living."

Some rescue workers said they were developing skin lesions from working in the foul environment, and federal health officials warned that the rashes could be just the beginning.

The first round of tests on samples of the floodwater covering much of the city revealed both fecal bacteria and lead in concentrations considered unsafe by the EPA.

"People should avoid direct contact with floodwaters as much as possible," he said. "We strongly advise people to use soap and clean water to clean off all exposed areas."

CDC Director Julie L. Gerberding said the now-documented hazard of the water should provide one more incentive for New Orleans's remaining residents to leave.

"The water is full of sewage. We know this is not safe. We know there are lots of intestinal illnesses that can be caused by ingestion of the water, and in some cases even just from contact with the water," she said. "For the evacuees who have not left the city, you must do so. This water is not going away anytime soon."

With the city mostly evacuated, emergency vehicles sped down the wrong way on interstate highways. Crews launched rescue boats from highway on-ramps. Helicopters filled the sky, some toting large buckets to douse fires that are breaking out in areas inaccessible to firefighter vehicles.

The Louisiana Superdome, the sports venue that became home to thousands of desperate evacuees in the storm's immediate aftermath, was severely damaged. Doug Thornton, vice president of the firm that manages the building, estimated that repairs would cost at least $100 million. But, he said, it is premature to consider tearing down the 30-year-old facility, which would cost as much as $600 million to replace.

Amid confusion about how officials should enforce the mayor's evacuation order, state officials said rescuers were removing as many as 1,500 people a day. In issuing his decree on Tuesday, Nagin said that law enforcement officers should force people to leave, if necessary. But that order has apparently been overruled by Louisiana officials, who estimated that 5,000 to 10,000 people remained in the city.

"We're not making people leave, but we're strongly encouraging them to," said Gov. Kathleen Babineaux Blanco (D). "We want them to leave because they become another part of the problem. We might have to save them."

Mike Good, a rescuer who arrived here from Colorado a week ago, said that some people initially refused to go but then "decided on the third or fourth pass to get out." Often, he said, they chose to leave after running out of food and water.

Maj. Steve Whiteaker, a rescue worker from Texas, said he and his men are encountering an increasing number of people who refuse to leave their homes. Some say they do not want to be taken to the Superdome or the convention center, for fear of the violence that rippled through those emergency shelters before they were evacuated. Others are just scared to go anywhere.

"See, a lot of people there are destitute and they don't have anything left, and they still don't want to give that up," Whiteaker said. "Sometimes it's just a picture hanging up on the wall, but they don't want to leave it."

One of Whiteaker's men reported pulling his boat up to a woman on her porch and asking her to leave. The woman shooed him away. "Get off of my garden," she said.

Health officials have no official estimate of how many died, although political leaders have speculated that the toll could rise well into the thousands. One state official said FEMA has 25,000 body bags on hand.

"It's an effort just to be prepared," said Bob Johannessen, a spokesman for the Department of Environmental Quality.

Fletcher reported from Washington. Staff writers Robert E. Pierre and Ceci Connolly in New Orleans; Jacqueline L. Salmon in Baton Rouge, La.; and David Brown and Juliet Eilperin in Washington contributed to this report.

Some people moved from their homes to the New Orleans Convention Center. Other residents refused to budge, saying they were worried about a repeat of violence at the shelter.

The National Guard searches for survivors downtown. In neighborhoods, rescuers cut open roofs to check.Firefighters futilely try to douse flames at a home in eastern New Orleans. Helicopters with water buckets have been sent to help battle fires.Larry Stann of St. Bernard Parish has been holed up in Cajun's Pub, which remained open during the storm.Sgt. Erin Evans of the Las Vegas National Guard checks Brittany Richardson's doll before her family is evacuated. Shelters have been set up nationwide.