The death toll from powerful tornadoes that ravaged central and southern parts of the United States is estimated to be approaching 300.

Members of the National Guard in the states of Alabama, Mississippi and Georgia are actively stepping up relief efforts after a state of emergency was declared in Alabama.

According to CNN, at least 280 people are estimated to have died from the tornadoes, including 194 just in Alabama. The report said the death toll is expected to rise.

The National Oceanic and Atmospheric Administration said the recent tornadoes were the deadliest to hit the U.S. since 1974 when a tornado killed 315 people.

U.S. President Barack Obama instructed the provision of federal assistance for relief efforts and helping tornado victims.