SIOUX FALLS, SD — Pounding rain and vicious winds pummeled Sioux Falls just after dark Tuesday evening. By around 11:30 p.m., with many in bed for the night, the worst damage was about to hit.

“I was lying in bed, watching TV and it sounded like a freight train going over the house. So I got up and dashed into my closet and felt like the roof was going to come off,” explained resident Julie Mericle.

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The National Weather Service on Wednesday confirmed there were three separate EF-2 tornadoes, packing up to 130 mile per hour winds, touched down.

Each of them tore narrow swaths of destruction through the southwestern side of town.

The twisters left at least 37 buildings, including two hospitals, a major shopping mall and several apartment buildings, heavily damaged or destroyed.

Homes in several neighborhoods were also damaged with roofs missing and trees torn from the ground.

Making matters worse, there was failure in the city’s weather warning system.

“Quite honestly, what happened with the system is we just had a human error issue,” explained Sioux Falls mayor, Paul TenHaken. “Only some of our sirens were activated.”

Apparently the system’s software allows an override function whereby a dispatcher can activate sirens for select parts of the city.

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More than 25,000 customers lost electricity at the peak of the storm. Most had power restored by late Wednesday morning. Amazingly, there were no fatalities and only a handful of minor injuries to those caught in the tornado’s paths.

Though not common, September tornadoes are never out of the question.

“Four of the past five years we had tornadoes here in Minnesota during the month of September,” explained WCCO-TV meteorologist, Mike Augustyniak.

Most tornadoes hit the upper Midwest in May, June and July. According to nearly 70 years of weather records, September has about six percent of all Minnesota tornadoes.

Augustyniak reminds us they can happen anytime, day or night.

“That’s why we tell people to have some way to be woken up if there is a tornado warning that affects your area,” Augustyniak added.

As cleanup gets underway, city leaders vow to straighten out another mess.

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Promising to find out what went wrong with a warning system meant to keep citizens safe all times of the year.