(CBS) Four long days and nights have passed since Hurricane Katrina pounded, flattened and drowned New Orleans and much of the southeastern Gulf Coast.

The death toll keeps rising and today one Louisiana senator said 10,000 people may be dead in his state, CBS News correspondent Dan Rather reports. Damage estimates for the entire hurricane zone have climbed as high as $100 billion.

More federal aid finally started arriving in the area today. The National Guard transported food and water, driving through streets in New Orleans that looked more like rivers. The Guard - or the cavalry as one general called them -- also brought their guns and are under orders to take back the violent streets of the city.

President Bush, criticized for doing too little too late, tried to comfort some residents in Mississippi and promised to restore law and order in New Orleans. The president said he was happy with the federal response to the disaster but he did concede he is not satisfied with the results.

The president spoke after the mayor of New Orleans said the federal government does not have a clue what is going on in his city. And as gasoline prices spike all over the country, Mr. Bush warned there may be gas supply problems this Labor Day weekend.

All week long, a team of veteran CBS News correspondents has been covering the deadly destruction and extraordinary misery caused by Hurricane Katrina. Rather asked John Roberts and Lee Cowan to take a step back from their daily reporting in the epicenter of the storm and share their impressions of what they've seen and felt.

"I've been to a lot of these hurricanes including Hugo in 1989 and Andrew in 1992, which were both considered to be some of the biggest storms to hit the United States with some of the most grievous damage," Roberts says. "But I have to be honest to say I have never seen anything like this, that the scope of the human suffering here in New Orleans is difficult to comprehend, let alone try to convey to viewers through video and through storytelling. There are so many people here who have nothing, who have nowhere to go and are not being helped."

He says he talked with people who were on the interstate highway for two days in the broiling sun: "No one had even come by to check on them, certainly nobody had dropped off water. There was some water that was being dropped off as of Thursday, but certainly not enough to take care of everybody here.

"And the scene at the convention center in downtown New Orleans was reminiscent of something we have seen before perhaps in places like Haiti, thousands of people just standing around, not knowing where to go, not knowing what to do."

Roberts shows a clip of on evacuee shouting, "We got a 3-week-old baby out here. They don't have no formula, no water and they want us to survive out here. Where's FEMA? Where's the mayor? We need some help out here."

Roberts points out that the federal response to Hurricane Andrew was criticized as sluggish. "But they still got lots of water in," he says. "They got those water buffalos that the National Guard brings in. They were distributing meals ready to eat and other relief supplies. It appears as though what happened was that the authorities locally put all of their chips into one basket, that basket being the Superdome and just about everything else fell through the cracks."

Amid so many compelling stories, Roberts says, are the ones that just sit with you and give you nightmares at night and make it difficult for you to sleep. One for him involved a 75-year-old woman. "She had been trapped in her house in the eastern section of New Orleans with water up to her chest," he recounts.

"She was finally rescued by a boat, they brought her to the interstate along with her husband of 53 years and they were left on the interstate. Cars, police cars and other emergency vehicles, were traveling up and down the interstate all night long. She was desperately trying to flag them down because her husband was having a seizure. They kept passing her by and her husband died at her feet. That was on Tuesday evening; yesterday, we went by the same area and that body is still sitting there."

Roberts tells Rather the single biggest problem is what to do with people who aren't at the Superdome. Buses took some to facilities in Houston, including the Astrodome, and Texas Gov. Rick Perry is accepting up to 50,000 more.

"But there are thousands, tens of thousands of other people in this area who just have no place to go," Roberts says. "We were shooting on the streets down in the eastern section of New Orleans on Thursday and people were just walking. We saw a man who was a Vietnam vet, who gave his service to the country. He was wounded, disabled, unable to walk. He was being pushed along on one of those carts that you would pile boxes on having no idea where to go, but he had to leave his neighborhood because there were no relief supplies coming into it. There was nobody whatsoever giving them any direction. Gangs of looters were roaming through the streets; he felt it was unsafe to stay there. But they didn't have any kind of direction other than to say they eventually wanted to get to Texas.

"And you see those stories repeatedly, everywhere across this city. That the sense of desperation among these people is growing and while the operations at the Superdome, seem by the end of the week finally to be getting into gear, there are just so many other people across the city of New Orleans and all of these other parishes who just have no help whatsoever."

Cowan, who also reported from New Orleans, tells Rather it reminds him last year's tsunami, with one key difference.

"That time around, it seemed as if the world came to a stop and all the attention was focused on helping the people of the tsunami," he says. And the people there got that sense and really appreciated that. I don't get that sense here at all. In fact, it is just the opposite, almost everybody that we've talked to feels like the world has forgotten them."

When he first got there, he says he went to one of these freeway overpasses that was essentially the high ground or the highest ground for people to get to. "The very first thing that happened, " he says, "we were mobbed by people saying 'Where's the water? Where's the food?' A woman grabbed us, took us over to the side of the bridge and told us to look over the edge. We did and there was obviously someone who had jumped to his death down there. And she said he'd been sitting there for two days saying, 'They're not going to bring the water, they're not going to bring the food, we're not going to make it.' And one day, he simply got up and jumped."

A day later, Cowan says, he was in a boat, trying to check out the hospital situation in downtown New Orleans when he found a patient, an actual patient still in his hospital gown, floating on a piece of plywood.

"He'd been there for a day and no one had picked him up," Cowan says. "We had to pick him up. We pulled him into the boat ourselves and took him back to the hospital that we think he came from."

There 's a sense of hopelessness there that he has never experienced certainly on any other story, including the tsunami, Cowan says.