Some officers told their superiors they were leaving, police officials said. Others worked for a while and then stopped showing up. Still others, for reasons not always clear, never made it in after the storm.

The absences come during a period of extraordinary stress for the New Orleans Police Department. For nearly a week, many of its 1,500 members have had to work around the clock, trying to cope with flooding, an overwhelming crush of refugees, looters and occasional snipers.

P. Edwin Compass III, the superintendent of police, said most of his officers were staying at their posts. But in an unusual note of sympathy for a top police official, he said it was understandable that many were frustrated. He said morale was "not very good."

"If I put you out on the street and made you get into gun battles all day with no place to urinate and no place to defecate, I don't think you would be too happy either," Mr. Compass said in an interview. "Our vehicles can't get any gas. The water in the street is contaminated. My officers are walking around in wet shoes."

Fire Department officials said they did not know of any firefighters who had quit. But they, too, were sympathetic to struggling emergency workers.

W. J. Riley, the assistant superintendent of police, said there were about 1,200 officers on duty on Saturday. He said the department was not sure how many officers had decided to abandon their posts and how many simply could not get to work.

Mr. Riley said some of the officers who left the force "couldn't handle the pressure" and were "certainly not the people we need in this department."

He said, "The others are not here because they lost a spouse, or their family or their home was destroyed."

Police officials did not identify the officers who took their lives, one on Saturday and the other the day before. But they said one had been a patrol officer, who a senior officer said "was absolutely outstanding." The other was an aide to Mr. Compass. The superintendent said his aide had lost his home in the hurricane and had been unable to find his family.

Because of the hurricane, many police officers and firefighters have been isolated and unable to report for duty. Others evacuated their families and have been unable to get back to New Orleans.

Still, some officers simply appear to have given up.

A Baton Rouge police officer said he had a friend on the New Orleans force who told him he threw his badge out a car window in disgust just after fleeing the city into neighboring Jefferson Parish as the hurricane approached. The Baton Rouge officer would not give his name, citing a department policy banning comments to the news media.

The officer said he had also heard of an incident in which two men in a New Orleans police cruiser were stopped in Baton Rouge on suspicion of driving a stolen squad car. The men were, in fact, New Orleans officers who had ditched their uniforms and were trying to reach a town in north Louisiana, the officer said.

"They were doing everything to get out of New Orleans," he said. "They didn't have the resources to do the job, or a plan, so they left."

The result is an even heavier burden on those who are patrolling the street, rescuing flood victims and trying to fight fires with no running water, no electricity, no reliable telephones.

Police and fire officials have been begging federal authorities for assistance and criticizing a lack of federal response for several days.

"We need help," said Charles Parent, the superintendent of the Fire Department. Mr. Parent again appealed in an interview on Saturday for replacement fire trucks and radio equipment from federal authorities. And Mr. Compass again appealed for more federal help.

"When I have officers committing suicide," Mr. Compass said, "I think we've reached a point when I don't know what more it's going to take to get the attention of those in control of the response."

The National Guard has come under criticism for not moving more quickly into New Orleans. Lt. Gen. H Steven Blum, the head of the National Guard Bureau, told reporters on Saturday that the Guard had not moved in sooner because it had not anticipated the collapse of civilian law enforcement.

Some patrol officers said morale had been low on the force even before the hurricane. One patrolman said the complaints included understaffing and a lack of equipment.

"We have to use our own shotguns," said the patrolman, who did not want to be identified by name. "This isn't theirs; this is my personal gun."

Another patrol officer said that many of the officers who had quit were younger, inexperienced officers who were overwhelmed by the task.

Some officers have expressed anger at colleagues who have stopped working. "For all you cowards that are supposed to wear the badge," one officer said on Fox News, "are you truly - can you truly wear the badge, like our motto said?"

The Police and Fire Departments are being forced to triage the calls they get for help.

The firefighters are simply not responding to some fires. In some cases, they cannot get through the flooding. But in others, they decide not to send trucks because they are needed for more serious fires.

"We can't fight every fire the way we did in the past and try to put it out," Superintendent Parent told a group of firefighters on Saturday morning at a promotion ceremony in the Algiers section of New Orleans, a dry area.

Even facing much more work than could possibly be handled, he said, it was important for him to take time out for two promotion ceremonies.

"The men need reinforcement," said Mr. Parent, who put on his last clean uniform shirt for the ceremonies elevating 22 officers to the rank of captain. "They need to see their leader and understand that the department is still here and not going to pot."