Power failures and wind damage to homes, barns and businesses are reported in Arkansas, Mississippi, Missouri and Tennessee.
Arkansas Governor Mike Huckabee is declaring five counties disaster areas.
The National Weather Service says wind gusts of up to 80 miles an hour were clocked in eastern Arkansas, where a tornado was confirmed.
The 150 mile an hour twister injured at least four people and damaged 18 homes and several other structures including a church and grain-storage bins.
A suspected tornado also caused some damage to a school in Indianola, Mississippi.
Children huddled in the halls and nobody was hurt.
Arkansas could get more heavy storms from another system expected to move through Monday.