Ten years ago Saturday, the most destructive natural disaster in U.S. history struck New Orleans and the eastern Gulf Coast. Hurricane Katrina killed an estimated 1,800 people, but it could have been far worse if not for what became known as "The Cajun Navy." Hundreds of people in hundreds of boats gathered in Lafayette, Louisiana, to rescue thousands trapped by floodwaters, CBS News' David Begnaud reports.

They are some of the starkest scenes from the floodwaters that overwhelmed New Orleans: Thousands of people on rooftops without food or water, begging for help. As many as 60,000 people tried to ride out the storm. So many could only wave and wait for rescue.

Former state Sen. Nick Gautreaux watched it all on television and received a very personal plea for help.

"I got a text from Walter Boasso," Gautreaux said. "He was a senator at the time that I served with the Senate, and his text was simple, 'My people are dying. I need help.'"

Gautreaux put out his own plea across local TV and radio.

"They announced, 'Anybody wants to go help the people of New Orleans please come to the Acadiana Mall,'" south Louisiana journalist Trent Angers said. "They expected 24, 25 boats. Between 350 and 400 boats and people showed up."

It was 4 a.m., two days after Katrina hit, and the mall parking lot was full. David Spizale was there.

"They might not have even used their boat or trailer in a long time," Spizale said. "So you had some axle problems, you had some boats that were askew on the trailer, but the spirit was I'm going to go help, I'm going to hitch it up."

Gautreaux recalls warning of victims drowning and armed robbers roaming the flooded streets.

"If you're afraid of death, possibly you get shot or killed, then this is not a place for you to come," Gautreaux said. "And I will tell you there's not a person that turned around."

What rolled out of Lafayette was a makeshift flotilla that has come to be called the Cajun Navy, an eight-mile convoy of boats that made the two hour ride to New Orleans. Altogether, the Cajun Navy is credited with rescuing more than 10,000 people from flooded homes and rooftops.

"It's still very painful," rescuer Sara Roberts said.

Ten years later, Roberts still gets emotional thinking about the people she saved.

"It's hard to talk about, hard to certainly think about," Roberts said.

She can't forget how desperate people were.

"How eager they were to trust people they didn't even know," Roberts said. "But they were just so grateful that someone cared about them."

It was a rescue effort that was initially stopped at the water's edge. Authorities told Cajun Navy members they could not launch for safety reasons, but they didn't listen.

"You saw people in New Orleans walking in chest-deep water with all of their possessions floating in a plastic garbage can, and you're looking at it and thinking this is in our country, and in our case, it's two hours down the road," Spizale said. "So we were hard-pressed not to go into action. That's where we wanted to be."

Along the way, they had a front row seat to so many selfless acts. Sara saw two men neck-deep coming out of a Walgreens near a high-rise full of elderly people.

"And I was just so frustrated and so angry that these people had looted and had broken in with all this tragedy around, and I later found those guys," Roberts said. "They had broken into the Walgreens to buy, I mean to get medical supplies for those elderly people."

Before David Billeaud and his friend, Keith Bates, could get around law enforcement and into the city, they slept in a parking lot overnight, listening to cries for help on a local radio station.

"There was people calling in, wanting help, and you couldn't sleep, just hearing them, the people calling in telling their situation," Billeaud said. 'Where they're located, they can't get anywhere. There's water everywhere."

Last week, for the first time since he was rescued, Father Hampton Davis had a chance to thank his rescuer, Nick Gautreaux.

"Thanks for not listening to those people who said don't go in there," Davis said.

The former senator rescued a group of seminarians and priests from Notre Dame Seminary, which was surrounded by looting and arson.

"I want to publicly tell the world how grateful the seminary was that you all were there for us, and when we finally got back home in January you were lifted up in prayer at every Mass," Davis said. "Know that."

"If we would have had to wait for the federal government to be down here to help people, you know how many people would have died?" Gautreaux said.

Gen. Russel Honore was put in charge of the federal response during Katrina.

This Louisiana native and three-star general saw to it that the priority of his men and women was search and rescue.

"We had 20,000 federal troops," Honore said. "We had 20 ships and over 225 helicopters."

Honore credits the Cajun Navy for doing much of the initial lifesaving.

"In reality most people are saved by neighbors and volunteers after a disaster than are saved by organized rescue people," Honore said.

Kathleen Blanco was Louisiana's governor when Katrina hit. This past week, she thanked the rescuers.

"We never had enough help, and when you came in, you just made all the difference in the world," Blanco said. "The Cajun Navy rescuers are true heroes. Louisiana people saved Louisiana people."

Angers and filmmaker Allen Durand have researched the accomplishments of the Cajun Navy. Angers wrote a book, and Duran made a documentary.

"They saved 10,000 people, and not a one of them thinks of themself as brave or courageous or as a hero," Durand said.

They were civilian hurricane heroes, whose boat propellers were, as the New Orleans Times-Picayune put it, "The sound of salvation."

"No one will ever know all the people that helped," Gautreaux said. "I won't know everyone who helped, but people that were part of it were part of history."