A congressional committee is investigating Amazon over safety concerns at the company’s warehouses.

The details of the investigation, which was sent via a letter to CEO Andy Jassy, will investigate the deaths of six Amazon workers who were killed when a tornado hit an Amazon warehouse in Edwardsville, Illinois.

The letter calls on Amazon to provide the committee with documents related to the tornado event. The committee also asked the company to provide its policies around extreme weather situations including emergency practices, disciplinary and termination policies.

The committee has set a deadline of April 14 to submit the documents.

The document was necessary because the committee said in its letter that “Amazon workers were reportedly required to stay on the job during deadly wildfires in California in 2018, extreme heat in the Pacific Northwest in Summer 2021, and dangerous flooding during Hurricanes Irma in 2017 and Ida in 2021.”