Residents flee failing dam with 90-minute warning

(CBS News) KENTWOOD, La. - Isaac is now a tropical depression moving north. The rain it left behind has lakes and rivers overflowing their banks, flooding streets and homes. A dam in southern Mississippi is at risk of imminent failure. 60,000 people are being evacuated downstream, including the entire town of Kentwood, La.

Firefighters and deputies drove through neighborhoods here. They spoke on loud speakers. They gave clear and simple directions: "You have 90 minutes. Pack what you can and go."

Kim Garmillion and her husband thought they were done running when they moved here from New Orleans. They were wrong.

"I think it's crazy we moved here after Katrina, and we are just hoping everything will be fine," Kim Garmillion said.

Isaac has already dumped more than 20 inches of rain along the Gulf Coast in three days, and it's still raining.

Dam water released, levee cut due to Isaac
Isaac pummels areas around New Orleans
Oil falls as Isaac heads inland
Escaping the floods in Plaquemines Parish

On Thursday, Mississippi's Lake Tangipahoa swelled beyond its banks. The lake is a 700-acre pool that feeds into rivers stretching more than 60 miles.

Authorities say they'll have to release some of its water. It is the only way to save some 60,000 people from having their homes overtaken by flood waters 17 feet deep.

So, local shelters filled up quickly. Cherrie Gibson said she wasted little time getting to one. All she brought was one bag and her family, saying she was "just trying to get safe."

It was the same motivation for families in Slidell, La., east of New Orleans. Police and National Guardsmen rescued nearly a hundred people -- the frail and the able bodied.

Rebecca Bass called 911 to save her and her two children: 1-year old Jacob and 7-year-old Jennifer.

"I was thinking I wasn't going to go swim because I don't know how," Jennifer said.

Dorothy Innerarity, 69, has lived here most of her life, she's partially paralyzed. In the rush, she left her medication behind.

"As long as my nose was out (of the water,) I'm okay," Innerarity said.

South of Slidell, in Plaquemines Parish, parts of the area are under 14 feet of water.

Back in Kentwood, Darrel Gordon thought about ignoring the mandatory evacuation.

"If not for those two girls, I would have stayed there," Gordon said.

Officials are pumping water off the lake and they tell say unless it rains much more, that should be enough.

More than two feet of rain is still expected in some places.