Coast Guard rescue swimmer Scott Holway has answered hundreds of pleas to save citizens from murky New Orleans floodwater in recent days, but on Thursday for the first time, a shoving match on a high balcony led to an urgent call for backup from a fellow lifesaver.

"Brett was on the balcony, and there were six people getting really pushy with him, so he called me and I went down, and we both dealt with it," said Holway, 40, of Cape Cod, Mass.

Dealing with it meant, first, muscling four men back into the house and slamming the door, so Holway could safely hoist two other people onto a hovering helicopter.

Amid 100-degree heat and dwindling food and water, the growing desperation among the thousands of people stranded in New Orleans is adding a new threat of hostilities to the dangerous and exhausting mission waged around the clock by about 100 Coast Guard aviators flying from a disaster headquarters here.

"These people want off these roofs," said rescuer Scott Rady, 34, of Clearwater, Fla. As a result, some are growing "a little combative," said Rady, one of about 50 rescue specialists performing six-hour missions plucking people to safety in helicopters. The flights back and forth to New Orleans are a key part of the rescue mission now in its fifth day, and they constitute the biggest operation in response to a natural disaster in recent Coast Guard history, commanders said.

An ugly turn in the attitude of desperate citizens has convinced many of the rescuers that, despite a massive relief effort, the situation in New Orleans in worsening.

Increasingly impatient after days of fruitlessly waving at aircraft, some residents now greet rescuers not with expressions of relief but with complaints. "They see planes flying around, and they're really frustrated," said Dustin Skarra, 34, of Vista, Calif.

"Before, people were excited." Now they ask, " 'Why weren't you here earlier? Why can't you take our luggage?' " Skarra said, when he returned to base after a predawn mission Thursday.

Coast Guard helicopters were grounded for an hour, along with other military aircraft, after reports that residents had fired at an Army evacuation chopper, Coast Guard officials said. To ensure greater protection, rescue swimmers who usually work alone are frequently operating in teams of two, and Coast Guard officials are avoiding dropping off single rescuers on rooftops.

The tensions are rising as Coast Guard crews continue to face an evacuation that appears more massive by the hour, according to interviews with several rescuers here. Already, teams from Mobile have saved 1,500 people, officials said. Holway and another rescuer pulled 62 people to safety in just seven hours Wednesday.

The teams recount inescapable images of human need, vivid even from high above New Orleans.

"When they hear the helicopters coming, they are almost like gophers hopping through the roofs," Rady said.

One or two people on a roof can often mean large families huddling out of view in the attic. In New Orleans, the rescues unfold almost organically, defying clear plans or territories to search because the need for help is everywhere. "They just say, 'Go fishing,' " Rady said.

To grab the pilot's attention, residents wave wildly and craft makeshift signs of cardboard, plywood or words scraped onto rooftops, with messages such as, "Two Kids, One Sick," or "Four People Need Help," crew members said.

At night, the stranded shine flashlights that make it easier for Coast Guard crews to spot them. One desperate mother of a 4-month-old infant stood on her apartment roof holding a full-length closet mirror, startling a Coast Guard team with the bright flashes created by the reflections of the helicopter spotlight.

Finding people is often a prelude to hazardous and strength-sapping rescues. Rescuer Joel Sayers discovered on a roof a woman whose husband was trapped in the attic, unable to use his legs.

"She was crying and begging me not to leave him behind," said Sayers, 32, of Dublin, Va.

So after taking the woman to a landing zone, Sayers borrowed an axe from firefighters and returned to carve a hole in the roof and rescue the husband.

Other swimmers had to break through rooftops with their bare hands, prompting the Coast Guard to begin outfitting all of them with axes. Gerald Hoover, 39, of Perry, Fla., used one to break through a window so he could lift a 160-pound woman into a rescue basket. He and his crew, their helicopter hovering, then had to work in concert to carefully lift the 70-year-old between her building and a tree so that the basket would not smash into either.

That incident showed how many New Orleans residents have gone to extraordinary lengths to help the frail. Hoover and his team would never have found the woman without the help of a boy who had been swimming back and forth to her second-story apartment to provide her with food.

The team was about to leave with seven members of the boy's family when he suddenly showed up.

Fear and panic are obstacles for rescuers, who use a harness similar to that worn by rock climbers to hoist people onto helicopters 100 feet in the air. Some people scream and cry, their terror so great that it overwhelms their desire to be saved.

"You just hold on to them and tell them it's going to be okay," said Coast Guard swimmer Joshua Micheltree of Hope Mills, N.C.

Families are often separated amid the urgent need to first rescue the elderly and the young, tugging at the sympathies of the Coast Guard rescue specialists.

Sayers took one teenage girl into his arms and watched her "cry as hard as I've ever seen anyone cry," her face screwed up with grief over leaving her parents. "I just kind of pushed her into the helicopter," he said. "They survived through this tragedy, and all they have is each other."

The sheer scope of the mission and its emotional toll is something the Coast Guard personnel say they will remember for the rest of their lives.

For Skarra, flying at night over the city of New Orleans presents an image as surreal as it is daunting. "Everyone is shining their flashlights," he said, "so as you're flying over, it's kind of like you see a sky full of sparkling stars. So which star do you pick?"

A Coast Guard helicopter moves into position. The growing desperation of stranded victims is adding a new threat of hostilities to the tough rescue mission. Coast Guard specialist Dustin Skarra said some residents greet rescuers with complaints: "They see planes flying around, and they're really frustrated."