Forty-five people made it out of the building, with one person airlifted to a regional hospital for treatment, Edwardsville Fire Chief James Whiteford said during a Saturday evening news conference.

"Earlier this afternoon, the response portion of this incident came to a close and we're now focused solely on recovery," Whiteford said.

The recovery phase is expected to take three more days and first responders will continue "to search the site for evidence of life," he said.

Amazon Worldwide Consumer CEO Dave Clark said the company's staff was saddened at the loss of life at the facility and beyond.

"Our thoughts and prayers are with the victims, their loved ones, and everyone who has been impacted by the storm's path across the U.S. We're continuing to provide support to our employees and partners in the area and across the communities affected by the storms. We also want to thank all of the first responders for their ongoing efforts on the scene," Clark said in a tweet.

The chief said approximately 150 yards of the building collapsed after the tornado touched down at 8:35 p.m. CT on Friday.