Pictured Wednesday, homes lie in ruins after a tornado blew through Pratt City, a neighborhood in Birmingham, Alabama (see map), earlier in the day.
The tornado was one of many spawned by a vast, violent storm system that has so far killed as many as 231 people in six U.S. states as of Thursday, according to CNN.
At least 131 people have died in Alabama alone, where several strong tornadoes tore through cities, Governor Robert Bentley told reporters Thursday.
"This could be one of the most devastating tornado outbreaks in the nation's history by the time it's over," CNN meteorologist Sean Morris said.
(Get tornado safety tips.)
ON TV: Witness: Tornado Swarm 2011 airs Sunday, May 29, 9 p.m. ET/PT >>