At least 18 people were killed across the central United States as tornadoes and other extreme storms hit several states including Texas, Arkansas, Oklahoma, and Kentucky, according to CNN on May 27. 

Nearly 109 million people spanning wide areas of the U.S. were under threat of large hail, damaging winds, and fierce twisters on Sunday, primarily across the mid-Mississippi, Ohio, and Tennessee River valleys. The extreme weather has caused power outages and forced people to take shelter across the region.

As severe weather continued to unfold across parts of the U.S., a heightened tornado watch designated as a rare "particularly dangerous situation" calling for "several tornadoes with a few intense ones likely" went into effect on Sunday, according to the Storm Prediction Center.