Flood waters from Hurricane Katrina fill the streets near downtown New Orleans

Residents who did not evacuate New Orleans face a new threat as floodwaters race through the low-lying city through breaches in area levees.

New Orleans mayor, Ray Nagin, says at least 80 percent of the city is already flooded.

The storm had blown out windows from many downtown buildings, and ripped holes in the roof of the Superdome arena, where some 10,000 residents sought shelter overnight from the storm.

Hospital officials say they are using emergency generators and are considering evacuating patients as the floodwaters rise.