The 'Extreme' team is in the Big Easy to help repair damage from Hurricane Katrina.

"Extreme Makeover: Home Edition" finishes up its 50-state tour with two rebuilds in the hard-hit New Orleans area for the season finale: a home for the Usea family and the Noah's Ark Missionary Baptist Church.

"The reason I think it is so significant and poignant [that we are finishing there] is that we are letting America and the world know that those people are still down there and still need help," designer MICHAEL MOLONEY tells ET. "It is phenomenal when you drive around and see what is still devastated, what is red tagged and waiting to be demolished."

The Usea family lives in Westwego, LA, which was hard-hit by Hurricane Katrina, but BRAD and LAURA USEA were lucky in that their home survived. Not so fortunate was Laura's mother GRACE, whose home was destroyed, as were those of Brad's twin brother CHAD and older brother CHRIS.

Brad and Laura took the entire family in without a second thought. Then in February, 2007, the area was again the source of devastation when tornadoes swept through, causing more damage and destroying the trailer in the backyard where Chris had been living.

That night both Brad and Chris, volunteer firefighters, worked to rescue those caught in the second storm, making them local heroes.

"These two brothers are very highly regarded in the community," Moloney says by way of explaining their selection. "They continued to step up and pluck people out of the water and do what they needed to do, knowing their own homes were lost. They were just solid guys. I think that is the definition of hero."

In New Orleans, in the wake of Katrina, Pastor WILLIE WALKER, after ensuring the safety of his own family, risked his life by going back to the devastation time and time again to help rescue hundreds and save many lives. And, even though his church  -- Noah's Ark Missionary Baptist Church -- was destroyed, he has since continued to work tirelessly to help the victims of Katrina. His selflessness made him a perfect choice for the "Extreme" team.

In order to get both projects done in just a week's time, "Extreme Makeover: Home Edition" called for a coalition of builders from all over the country -- and were pleasantly surprised by the response and by the locales who turned out.

"In New Orleans, everybody has been called upon for two-and-a-half years now," Moloney explains. "Everybody has been volunteering and giving and giving. And we show up and -- all the labor is volunteered -- want to build a house in a week, and they were there."

"Extreme Makeover: Home Edition"'s two-part season finale airs Sunday, May 18, from 7 to 9 p.m. on ABC.