SIOUX FALLS, S.D. — Sioux Falls residents woke up Wednesday, Sept. 11, to find themselves a city under siege.

Overnight, three powerful tornadoes and devastating winds carved destruction across parts of the city, ripping open medical facilities and businesses, flipping cars, uprooting trees and cutting power to about 25,000 residents.

Officials estimate one tornado, with winds topping 125 mph, slammed the city’s populous south side just before midnight, devastating a portion of West 41st Street, Sioux Falls' busiest commercial corridor, and surrounding neighborhoods. Another tornado ripped through medical facilities along West 69th Street with 130 mph winds. Another cut through a residential area on the city's southeast side.

All three tornadoes were rated EF-2 on the five-point Enhanced Fujita scale, the National Weather Service office in Sioux Falls said after assessing the storm damage.

Straight-line winds calculated at 90-100 mph buffeted much of the rest of the city. While the National Weather service issued warnings with plenty of time to take cover, most of the city's outdoor sirens failed to sound as the tornadoes tore into Sioux Falls.

No casualties or serious injuries were reported. But numerous residential streets and a stretch of West 41st Street was closed to traffic as emergency crews cleared debris and downed trees and restored downed power lines.

Lyndsay Anderson, who lives on the 3200 block of South O'Gorman Drive, along one tornado track, said she and her family hustled into the basement as the twister roared in.

"It was nuts, just nuts," she said. "It sounded like we were being invaded, like someone was beating the sides of our house with sticks."

The roof of an apartment building behind her home sailed off, crashing partly in her back yard, with the rest landing a block east. The tornado splattered shredded pink insulation from the building over every nearby covered surface, including downed and twisted trees in nearly every yard around Anderson's home.

The tornado that ripped through Sioux Falls late Tuesday night, Sept. 10, with 125 mph winds damaged many buildings in the city, including stripping trees and flipping cars in a swatch of damage on the city's south side. Jeremy Fugleberg / Forum News Service
The tornado that ripped through Sioux Falls late Tuesday night, Sept. 10, with 125 mph winds damaged many buildings in the city, including stripping trees and flipping cars in a swatch of damage on the city's south side. Jeremy Fugleberg / Forum News Service

About 5,500 Xcel Energy customers remained without power as of 4:30 p.m., but the utility had pledged to bring in additional crews Wednesday to help restore power.

The tornadoes and winds collapsed or wrecked the integrity of 37 buildings, said Sioux Falls Fire Chief Brad Goodroad, including a Tuesday Morning store, a Jo-Ann Fabrics, a Pizza Ranch and an Advance Auto Parts.

The tornado along West 69th Street damaged several medical facilities on the south side of the city, including the Avera Heart Hospital of South Dakota and the adjacent Avera Behavioral Health Center. The tornado blew out the heart hospital's front doors, many windows and the emergency room bay doors, snapping large trees in half and throwing them into cars in the parking lot outside.

A tornado that struck Sioux Falls late Tuesday night, Sept. 10, blew out doors and glass at the Avera Heart Hospital of South Dakota. Jeremy Fugleberg / Forum News Service
A tornado that struck Sioux Falls late Tuesday night, Sept. 10, blew out doors and glass at the Avera Heart Hospital of South Dakota. Jeremy Fugleberg / Forum News Service

Avera staffers woke up 102 patients in the Behavioral Health Center to gather them in the center of the building. Seven Avera staff received only minor injuries as ceilings gave way, he said.

Avera was finding new housing for its patients at the center and was working with state officials to potentially relocate some patients to state facilities. Avera McKennan President and CEO Dave Flicek said the center was so badly damaged, it's expected to take three to six months to reopen.

At the heart hospital, Avera medical providers saved a patient's life from a "cardiac event" even as the tornado roared through, said heart hospital president Mick Gibbs.

"This was the worst tornado I've ever seen," said Gibbs, who grew up in tornado-prone southeast Kansas. "I couldn't be more proud of the way this wonderful community responded, in private and public."

The city failed to sound all 77 of its outdoor warning sirens across the city as the storm struck, Mayor Paul TenHaken said in a morning briefing. Only sirens in southeast Sioux Falls sounded, he said, due to “human error" when a dispatcher who triggered the warning misheard which part of town to turn on the sirens.

“That can’t happen again,” TenHaken said.

But he praised the city for its resilience in the face of the storm, as evidenced by the lack of injuries and the city's quick swing into cleanup mode. The city set up a central website for storm cleanup and response information at siouxfalls.org/storm. The Red Cross set up a shelter and the city set up two tree disposal sites as residents clear downed timber in their yards and driveways.

The cleanup Wednesday was not without its oddities and confusion. Reports of looting were inaccurate, TenHaken said. Employees of the heavily damaged auto parts store were checking out the structure and passersby mistakenly reported them for looting.

The city took to Twitter to say another Twitter account had been posing as the city and distributing incorrect information. Officials also begged residents to avoid clogging cluttered streets to get a look at the damage, although it was clear many ignored the request.

The devastated Advance Auto Parts on West 41st Street provided perhaps the most spectacular perspective on the erratic power of the tornado that struck it. Shelves of car parts tilted in the store, whose skin on its east side was entirely stripped away, exposing the interior. The wall was flung on the ground mere feet from the adjacent Burger King.

Chad York, Burger King district manager, smoked a cigarette as he quietly sat outside his store Wednesday afternoon, waiting for the power to come back on. The tornado left his fast food restaurant almost unscathed, pulling off only one small awning, wrecking its street sign and removing a panel on a roof-mounted air-conditioner, conveniently dropping it nearby.