Hurricane Isaac: Dangerous Flood Zone Grows

Entire Neighborhoods are underwater in the Gulf Coast.
3:00 | 08/31/12

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Transcript for Hurricane Isaac: Dangerous Flood Zone Grows
That ugly storm, isaac, is definitely making its mark here around the gulf coast. And now, it continues to move up to the north and eventually east. Here's what's going to happen. It will weaken, it has. It's become a post-tropical depression. Still could drop a lot of rain in places, up to eight inches as it heads into the ohio river valley. Making its mark not only here on the coast, but around the country, as well. Scenes from above for the first time. Scenes of utter devastation. Where there was once dry land, now only gulf and no coast. Hundreds of miles of coastline are under water this morning. Soaked by more than a foot of additional rain thursday. As isaac continued to pound this area for a third day. It's confusing. Reporter: Overrunning roads and causing trees and power lines to fall. There it goes. Reporter: Many neighborhood shocked by the devastation. We've never flooded this bad. Reporter: Those who weren't rescued by police, the national guard, forced to improvise. We got running really quick. It's horrible. Reporter: Along the tangipahoa river, more than 50,000 residents were told to evacuate, as the dam that protected their homes, threatened to give way. This tornado that caused all this damage came through. Just literally exploded the roof off the house. Reporter: Homes that weren't underwater, torn apart by wind. And this morning, while the rain may finally have stopped, the misery has not. More than 750,000 households across 4 states are without power. And many roads remain impassable. They have no means of communication. Phone lines are down. Electricity is down. We are problems. Isaac still poses a threat for the nation. I'll be showing you coming up with the other weather. We're going to matt gutman, part of the extreme team this week. Matt is in slidell, louisiana. Matt, good morning. Reporter: Good morning, ginger. Not just residents entering thousands of homes. But what's in this water. Sewage systems have backed up. Pumping stations are pumping into this water. It's highly contaminated. Communities here are dark. 75% of metro new orleans is still in the dark. 400,000 people without power. Basics, still hard to come by. We've been trying to find gas for two days. Very little luck.

This transcript has been automatically generated and may not be 100% accurate.

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