Kathleen Blanco, governor of Louisiana, called on the city of New Orleans to evacuate as waters continued to rise. ”We absolutely must evacuate the people in the dome and other shelters in the city,’’ she said on CNN. ”It’s a logistical nightmare.”

The US military on Wednesday added Navy ships, including two helicopter assault vessels and the hospital ship Comfort, and search troops to a relief effort in the wake of Hurricane Katrina.