( CNBC.com )

The House Oversight Committee on Friday launched an investigation into Amazon’s labor practices, demanding the company turn over information related to a deadly warehouse collapse in Illinois last year.

In a Thursday letter addressed to Amazon CEO Andy Jassy, Oversight’s chairwoman, Rep. Carolyn Maloney, D-N.Y., and Reps. Alexandria Ocasio-Cortez, D-N.Y., and Cori Bush, D-Mo., wrote that they are “concerned by recent reports that Amazon may be putting the health and safety of its workers at risk, including by requiring them to work in dangerous conditions during tornadoes, hurricanes, and other extreme weather.”

The lawmakers requested documents related to Amazon’s handling of a tragic warehouse collapse at one of the company’s facilities in Edwardsville, Illinois. Last December, a tornado ripped through the warehouse, known as DLI4, causing the 1.1 million-square-foot facility’s roof to collapse, while 40-foot-tall, 11-inch thick walls on the sides of the building fell inward.

Six workers were killed. Many of the victims were delivery drivers, who pulled into the facility just before the storm hit and frantically fled to a bathroom in an area of the building that was hit by the storm.

In the aftermath of the tragedy, Amazon workers near the Edwardsville facility told CNBC they felt the company had inadequate safety protocols for severe weather events.

DLI4 employees also alleged that they were “threatened by their supervisors with termination or other adverse employment consequences” if they left their workplace to seek shelter, the lawmakers wrote. One of the victims, Larry Virden, reportedly texted his girlfriend, “Amazon won’t let us leave,” according to the New York Post.

Amazon spokesperson Kelly Nantel previously said the company was looking into “every aspect” of the incident.

In addition to the Edwardsville tragedy, the lawmakers said they were also troubled by Amazon’s response to other extreme weather events impacting warehouse workers. They pointed to a dangerous heatwave last year in the Pacific Northwest, during which employees claimed they toiled in warehouses that reached 90 degrees. The lawmakers said Jassy must respond by April 14.

“This investigation will inform legislative efforts to curb unfair labor practices, strengthen protections for workers, and address the effects of climate change on worker safety,” the lawmakers wrote.

Nantel told CNBC in a statement Friday: “Our focus continues to be on supporting our employees and partners, the families who lost loved ones, the surrounding community, and all those affected by the tornadoes. We will respond to this letter in due course.”