The tornado that caused a partial building collapse at an Amazon warehouse in Edwardsville, Illinois, killing six people, was an EF-3 tornado, the National Weather Service reports.
Citing preliminary storm damage survey results, the NWS reported the worst damage was northeast of Pontoon Beach in/around the Amazon facility.
Top wind speeds were estimated to be around 155 mph, according to a tweet from the NWS office in St. Louis.
An EF-3 indicates estimated wind speeds between 136 and 165 mph and an EF-1 means wind speeds were believed to be between 86 and 110 mph.
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Six people were killed when a portion of an Amazon building collapsed in the downstate community late Friday night. At least one person was injured, and 45 others were rescued, authorities said.
First responders said crews were "still searching for signs of life" Saturday evening, noting search efforts will likely continue for three additional days.
A storm caused a series of tornadoes to tear through multiple states from late Friday evening to early Saturday morning, resulting in dozens of deaths.