Rescuers scoured wreckage in Mississippi yesterday for any survivors of the deadly tornadoes that tore through the southern US state, killing at least 10 people and destroying dozens of homes.

The National Guard fanned out across affected areas, using Humvees to reach hard-hit Yazoo county, nestled in the hills that rise sharply out of the Mississippi delta. Others surveyed the damage from Blackhawk helicopters.

Official said three children aged three months, nine and 14 were among the dead in Choctaw county.

The toll could well mount as rescuers clear the debris from Saturday's storms, which tore roofs off buildings, reduced homes to splinters, overturned vehicles, downed power lines and toppled trees onto the roads.

Survivors told dramatic stories of narrow escapes from tornadoes that were up to 1.6 kilometres wide and packed winds of nearly 165 miles per hour, according to meteorologists.

Sandra Grayson, who was sitting on her front porch just outside Yazoo City when she saw the tornado come tearing over a nearby hill, ran and hid inside her bathroom.

"I could hear all around me the trees twisting and swaying," she told The Clarion-Ledger newspaper. "I asked God to hug us because it was like you could just tell you were looking in the eyes of death."

Mississippi governor Haley Barbour declared a state of emergency in 17 counties devastated by the storms and twisters, while the federal government and the American Red Cross dispatched rescue teams to the disaster zone.