CRYSTAL SPRINGS, Ark. -- Powerful spring storms roared through parts of the South on Friday, toppling trees, smashing buildings and killing at least 10 people, including two sets of parents and children who were huddled together as the winds raged outside their homes.

It was the deadliest storm of the season so far. Several tornadoes accompanied the onslaught, but much of the damage was attributed to straight-line winds -- sudden, violent downbursts that struck with hurricane force in the middle of the night.

The storms began late Thursday in Oklahoma, where at least five tornadoes touched down and two people were killed. The system then pushed into Arkansas, killing seven more. Dozens of others were hurt.

By midday Friday, the storms marched into Tennessee, Louisiana and Mississippi, and later into Georgia and Alabama, where one person was killed. At least three twisters touched down in Mississippi, where a state of emergency was declared in 14 counties, causing widespread damage but only one serious injury.

Arkansas Gov. Mike Beebe said he had never seen the state suffer so many deaths from straight-line winds. Tornadoes and floods cause most of Arkansas' storm-related fatalities.

Unlike tornadoes, which develop from columns of rotating air, straight-line winds erupt from a thunderstorm in downdrafts, then spread across the landscape in all directions.

Teams from the National Weather Service worked Friday to learn more about what caused the damage.

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