The site of a roof collapse at an Amazon.com distribution center in Edwardsville, Illinois.
Drone Base | Reuters

The Occupational Safety and Health Administration is investigating a collapse at an Amazon warehouse in Edwardsville, Illinois, an agency spokesperson said Monday. The collapse was caused by a tornado that devastated the area and killed six workers.

A tornado on Friday hit the Amazon delivery depot, known as DLI4. Six workers were killed, one was injured and 45 people were rescued safely, Governor J.B. Pritzker said in a press conference Saturday.

The storm was just one of at least 30 tornadoes that left a path of destruction across several states, including Kentucky, where more than 60 people were confirmed dead.

The National Weather Service said a tornado touched down in Edwardsville, Illinois, at approximately 8:35 p.m. local time on Friday. Walls on both sides of the warehouse collapsed inward, while the roof collapsed downward, Edwardsville Fire Chief James Whiteford said in a news conference Saturday.

Site leaders at DLI4 told employees on duty at the facility to take shelter around 8:16 p.m. local time, Amazon said. The tornado likely formed in the parking lot then rolled through the site, Amazon said.

OSHA has six months to complete its probe, issue citations and propose monetary penalties if violations of workplace safety and or health regulations are found, OSHA spokesperson Scott Allen told CNBC in a statement. The agency has had compliance officers at the warehouse since Saturday to provide assistance, Allen said.

Representatives from Amazon didn’t immediately respond to a request for comment on the OSHA probe.

Amazon previously said it was working to monitor the situation and support the recovery, including assisting with local relief efforts in Edwardsville.

“We’re deeply saddened by the news that members of our Amazon family passed away as a result of the storm in Edwardsville, IL,” Amazon spokesperson Kelly Nantel said in a statement. “Our thoughts and prayers are with the victims, their loved ones, and everyone impacted by the tornado.”

WATCH: Six Amazon employees dead after tornado hits Illinois warehouse