When Hurricane Katrina struck New Orleans in late summer 2005, tens of thousands of people lost their homes. Among them was former Cowboy Mouth guitarist Paul Sanchez.

So, in 2009, when a screenwriter friend of his, Colman deKay, suggested that Sanchez read a Katrina-related book by New Yorker writer Dan Baum called “Nine Lives,” Sanchez was vehemently opposed to it at first.

“I’d lost my home in the flood, and my wife and I were trying to rebuild,” Sanchez said. “I had quit the band I was with for 15 years (Cowboy Mouth). So I told him, ‘No, I just can’t read anything more about the flood. I’m overwhelmed with it.’ ”

DeKay assured him it wasn’t just about Katrina but that it dwelt primarily on the 40 years before the hurricane, starting with a previous killer storm, Betsy. Sanchez finally agreed to read the book and after he did, deKay suggested turning it into a musical.

Sanchez, who said he had no experience with musicals to that point, was initially hesitant. But after giving it some thought, he wrote the lyrics to a song. Then the two of them started writing songs together, eventually penning nearly three dozen.

The “Nine Lives” Baum profiled in his 2007 book were nine New Orleanians from different walks of life representing neighborhoods from the mansions of St. Charles Avenue to the shotgun houses of the Lower Ninth Ward. The songs Sanchez and deKay composed were about these nine people and some of those who were close to them, and what their Katrina experiences were.

When the initial show opened at LePetit Theatre in May 2011 featuring 39 songs, “It was more like a rock show or a song cycle than a theatrical piece,” Sanchez said. “Some of our key people felt like it had the ability to move into more theatrical musical territory, and that’s what it’s become now.”

The latest incarnation of “Nine Lives,” with added narrative from a libretto by Kimberly Kaye, opens Wednesday, Aug. 27, at Le Petit and runs for three nights.

It features an all-star cast of singers and performers, headlined by Tony Award-winner Michael Cerveris, former “Mad Men” TV star Bryan Batt and Sanchez himself portraying longtime Orleans Parish coroner and trumpeter Frank Minyard.

Other performers in the current cast include Shamarr Allen, George Sanchez, Jesse Moore, Robin Barnes, Vance Vaucresson, Alex McMurray, Debbie Davis, John Michael Haas, Ashley Rose Bailey, Tara Brewer, Erica Falls, Bill Malchow, Craig Klein and Sam Craft. Jim Fitzmorris directs.

Among the colorful characters portrayed are JoAnn Guidos (Cerveris), a transgender bar owner in the Faubourg Marigny; Kathy Guidos (Davis), the bar owner’s ex-wife; Wilbert “Da” Rawlins (Vaucresson), Irma Thomas’ former drummer; his son Wilbert Jr. (Allen), former band director at O. Perry Walker High School; Wilbert Jr.’s wife, Belinda Carr (Barnes); Billy Grace (Batt), a former Rex; his father-in-law George Montgomery (George Sanchez); and Grace’s wife, Sweet Anne (Brewer).

Other characters include singer Irma Thomas (Falls); Ronald Lewis (Moore), a community activist and owner of the House of Dance and Feathers Mardi Gras Indian museum; and Tim Bruneau (McMurray), a former New Orleans cop with a reputation for brutality.

Sanchez described the latest “Nine Lives” version as “a work in progress,” an assessment shared by Fitzmorris, who is working with the cast and other principals on the show’s format transformation.

“We wanted to create a book for the show that complemented the music, rather than just having music standing alone,” said Fitzmorris, who is a freelance writer for The New Orleans Advocate. “The songs would give way to dialogue and monologues that would then take us into the next song, bridging the gap between songs and developing the characters.

“So this is definitely a work in progress,” Fitzmorris said. “What you’re seeing at this stage is how the music links up with a coherent book. It’s a musical now. It has a beginning, a middle and an end. That’s the crucial difference.”

So where does it go from there, Fitzmorris was asked. “If I was going to guess, I’d say we’ll do this one then we’ll all sit down and figure that out,” he replied. “And once we do, we’ll take the next step, which should bring us closer to a finished product.”