Amazon’s handling of the deadly Edwardsville, Illinois warehouse collapse in December is drawing criticism from key figures in Congress. Motherboardreports that Senator Elizabeth Warren and representatives Alexandria Ocasio-Cortez and Cori Bush have sent a follow-up letter to Amazon CEO Andy Jassy and chairman Jeff Bezos criticizing the company’s “disappointing” response to an initial series of questions about the Illinois warehouse’s safety. They said OSHA’s findings described a “wholly inadequate safety culture” that may have played a role in the deaths of six facility workers.

The data pointed to “serious concerns” about safety training at the Edwardsville location, the politicians wrote. While OSHA didn’t fine or otherwise punish Amazon, its investigation contradicted the company’s statements about preparedness. Staff didn’t participate in emergency drills that might have protected them from the tornado, and some didn’t even know the location of the designated shelter area. And while Amazon claimed the warehouse had an Emergency Action Plan, OSHA said the company neither customized it for the area nor followed it properly.

The investigation and Amazon’s response suggested the firm only did the “bare minimum” or less to protect workers, according to the politicians. They added that there was evidence of injuries and exploitation elsewhere, and urged Amazon to honor the House Oversight Committee’s request for documents as part of its own inquiry.

We’ve asked Amazon for comment. The tech giant said in its response letter that safety was its “top priority” and defended its practices at the Edwardsville warehouse. Bezos told shareholders roughly a year ago that Amazon needed to improve its treatment of employees, but his focus was on reducing repetitive strain injuries and general safety projects, not disaster preparedness. The retailer acknowledged some of the calls for reform by permanently allowing cellphones on-site.

Whatever Amazon’s answer to this latest letter, it’s likely to face considerably more scrutiny. On top of the House probe, Amazon is dealing with multiple lawsuits accusing the company of negligence that led to deaths and injuries at the Illinois hub. There’s still plenty of pressure to change, and Amazon might not succeed in resisting political demands.