Dozens of tornadoes ripped through the southern United States, killing at least 50 people and injuring hundreds of others on Tuesday and Wednesday.
At least 50 tornadoes are believed to have touched down across the states of Tennessee, Arkansas, Kentucky, Mississippi and Alabama.
The powerful storm system killed at least 24 people in Tennessee, 13 in Arkansas, seven in Kentucky and four in Alabama.
Rescue crews have been going door-to-door in search of more victims.
President Bush called the governors of the affected states to offer them consolation and support.
The tornadoes injured at least 149 people in the state of Tennessee alone.
The storms demolished a shopping mall in Memphis, and in the nearby city of Jackson, several students had to be rescued from the rubble after a twister destroyed their college dormitory.
The deadly twisters left large areas of destruction, with homes and other buildings ripped apart, vehicles overturned and debris scattered throughout the region.
The storm system produced the deadliest outbreak of tornadoes in the United States in nearly nine years.
Some information for this report was provided by AFP, AP and Reuters.