Black Elk Energy last week confirmed that a second worker died as a result of an accident on a rig off the coast of Louisiana mid-November.
Workers on the platform sparked a blaze while cutting into a pipeline that contained oil. The rig wasn't in service at the time of the incident and no visible sheen was associated with the accident.
Democratic House leaders called on Black Elk to respond to requests for more information by Dec. 10.
"In order to better understand how and why this incident occurred, we ask that you provide our staff with a briefing on the explosion, its possible causes and any remedial efforts your company intends to take as a response to this incident," a letter to Black Elk President John Hoffman read.
The company said it was cooperating with the investigation into the accident. Investigators with the U.S. Bureau of Safety and Environmental Enforcement have started a probe and the company was subpoenaed by the U.S. Chemical Safety Board for its investigation.