Residents across several southern US states have been assessing damage and picking up the pieces after tornadoes and strong winds caused widespread damage and killed at least two people.

A total of 73 tornado warnings and 120 severe thunderstorm warnings were issued from Tuesday afternoon to Wednesday morning, said Matthew Elliott, a meteorologist at the Storm Prediction Center in Norman, Oklahoma, the United States.

Forecasters had warned of the threat of strong twisters capable of tracking long distances on the ground as a severe weather outbreak erupted in the deep south.

Residents of several towns across Louisiana and Mississippi took cover as tornado sirens blared late on Tuesday.

Heavy thunderstorms rolled from eastern Texas to Georgia and as far north as Indiana. The National Weather Service confirmed that tornadoes hit the ground in Mississippi on Tuesday evening.

Significant tornado damage was also evident in the Flatwood community north of Montgomery, Alabama, where two people were killed as a tree struck their home, said Christina Thornton, director of the Montgomery County Emergency Management Agency.

Tornadoes damaged numerous homes, destroyed a fire station, briefly trapped people in a grocery store and ripped the roof off an apartment complex in Mississippi.

More than 25 million people were at risk from the vast storm system. The national Storm Prediction Center said in its storm outlook that affected cities could include New Orleans in Louisiana; Memphis and Nashville in Tennessee; and Birmingham in Alabama.