NEW ORLEANS � To Louisiana's attorney general, the doctor and two nurses arrested this past week are murderers. But many in the medical community are outraged at the arrests, saying the three caregivers are heroes who faced unimaginable horrors as Hurricane Katrina flooded the city and trapped them and their patients.

Dr. Anna Pou and nurses Cheri Landry and Lori Budo were accused of being principals to second-degree murder in the deaths of four patients at Memorial Medical Center three days after Katrina hit. The charge carries a mandatory life sentence, though the state will turn the case over to the New Orleans prosecutor, who will decide whether to ask a grand jury to bring charges.

Pou, Landry and Budo are accused of killing four patients, ages 61 to 90, with morphine and a powerful sedative called Versed.

Dr. Ben deBoisblanc, director of critical care at Charity Hospital, said he and others are angry at the accusations against a doctor and nurses who risked their own safety, and provided care in a chaotic and frightening situation.

"This doctor and these nurses were heroes. They stayed behind of their own volition to care for desperately ill people. They had an opportunity to leave and chose not to," he said.

Memorial Medical was swamped with 10 feet of water and isolated by Katrina's flooding. The 317-bed hospital had no electricity and the temperature inside rose over 100 degrees as the staff tried to tend to patients who waited four days to be evacuated.

Attorneys for the trio say they are innocent. DeBoisblanc and others fear the accusations may discourage other health professionals.

"We have people who are volunteering their services and putting their lives on the line. It's going to make it less likely they'll do that in the future," said Dr. Peter deBlieux, an emergency room and intensive care doctor who stayed at Charity Hospital during Katrina.

DeBoisblanc said it's also likely to make doctors less eager to return as the city tries to recover from the hurricane.

"If you think that going after physicians and nurses while hardened criminals are ruling this town, if you think that's an image that's going to bring people back, you've got to be kidding yourself," he said, noting the recent rash of violent crime in New Orleans.

Kris Wartelle, a spokeswoman for the attorney general's office, said the agency had to investigate the claims at Memorial because it must enforce the law.

"Where is the sympathy for the victims? Why is there no outcry for the people who would have not died had they gotten out?" she said. "These are not terminal people begging to be put out of their misery."

Pou, Landry and Budo were the first medical professionals charged in a monthslong criminal investigation into whether many of New Orleans' sick and elderly were abandoned or put out of their misery in the days after the storm.

"This case is not over yet," said Louisiana Attorney General Charles C. Foti.

Hundreds of people were stranded in the hospital with no power to run lights or elevators and no running water. Anyone willing to carry a gun was deputized to watch the entrances as people broke into nearby buildings.

"We had no communication floor to floor, much less to the outside world. We were surrounded by water. It was hotter than Hades," said Dr. Gregory Vorhoff, who was at Memorial after the storm but left to seek help before the alleged killings. "It was as bad as you can imagine."

Under such conditions, even patients who might have been able to walk or were relatively stable before Katrina could easily have lapsed into critical condition, doctors say.

"It's very easy for a relatively healthy person to go down quickly," said Dr. Daniel Nuss, Pou's department head at Louisiana State University, where Pou has given up clinical duties until the case is resolved.

He and other doctors said the morphine and Versed that investigators found in the patients' bodies are commonly given to relieve suffering and anxiety.

"If you didn't find sedatives and analgesics in these people, I would think that was inhumane," deBoisblanc said. "The very fact that you found these drugs means nothing."