US inspectors launch probe into Amazon warehouse collapse during tornado

Crews move in heavy equipment for search and rescue operations at the Amazon distribution centre in Edwardsville (Daniel Shular/St. Louis Post-Dispatch via AP)

US regulators have opened an investigation into the collapse of an Amazon warehouse in Illinois after it was struck by a tornado on Friday, leaving six people dead and another in hospital.

Occupational Health and Safety Administration inspectors, who have been at the site in Edwardsville since Saturday, will look into whether workplace safety rules were followed and will have six months to complete the investigation, said spokesperson Scott Allen.