Six people were killed Friday when a portion of an Amazon building collapsed in downstate Edwardsville during a severe weather outbreak, state and local officials said Saturday, as the operation shifted to a recovery mission.

Multiple workers were killed when a portion of an Amazon warehouse, located in the 3000 block of Gateway Commerce Center Drive South, collapsed during what the National Weather Service confirmed as an EF-3 tornado, according to local fire authorities.

At a news conference Saturday evening, Edwardsville Fire Chief James Whiteford stated that one person was injured, and 45 people were rescued.

At least one person was taken to an area hospital, and others suffered minor injuries that were treated at the scene.

Officials have not yet determined how many victims were hurt in the collapse or how many are still unaccounted for as workers were in the midst of a shift change when the tornado struck at about 8:30 p.m.

First responders continue to face a variety of obstacles as they comb through the wreckage, including fallen power lines and collapsed water lines in the area.

Structural engineers were called to the scene to determine if the concrete portions of the building were secure enough to allow firefighters to continue their search for victims.

Whiteford said crews were “still searching for signs of life” Saturday evening, noting efforts will likely continue for three additional days.

Amazon management was on scene to help identify individuals who work in the structure, but no official number of workers inside the building has been established.

In a statement, Amazon officials say that they were “deeply saddened” by the tragedy, and that they will take steps to assist employees and families impacted by the weather event.

“We’re deeply saddened by the news that members of our Amazon family passed away as a result of the storm in Edwardsville,” a spokesperson said in a statement. “Our thoughts and prayers are with the victims, their loved ones, and everyone impacted by the storm. We also want to thank all the first responders for their ongoing efforts on-scene.”

Speaking alongside local authorities Saturday evening, Illinois Gov. J.B. Pritzker offered condolences to those who lost loved ones in the collapse.

“Everyone assumes that they’ll be safe at work,” he said. “Families say goodbye in a routine fashion when their loved ones go off to their jobs. We don’t think that they’ll never come home. It’s devastating.”

Amazon says it will “provide support to our employees and partners” in the aftermath of the storm.

The deaths reported are but a few of at least 70 casualties feared after a storm caused a series of tornadoes to tear through multiple states from late Friday evening to early Saturday morning.