One person was killed and three others injured last month in an offshore explosion on a oil and gas platform in the Gulf of Mexico.

The blast occurred as workers were cleaning a heater treater that separates oil from other liquids on Fieldwood Energy’s Echo Platform just before 3 p.m. Nov. 20. The platform is located 12 miles off the Louisiana coast. The workers were employed by Louisiana-based Turnkey Cleaning Services Gulf of Mexico.

Two of the injured workers, Colte Cahanin, 21, and Seth Cormier, 19, have filed lawsuits against facility owner Fieldwood Energy and Island Operating Co., which was also contracted to work on the site. The lawsuits allege that the Houston-based companies failed to provide a reasonably safe work environment and ensure equipment was properly maintained. The claims also say the companies failed to ensure the heater treater was cleared of flammable materials and gases.

“These defendants failed to properly ensure the heater treater was cleared — and in essence turned over a disaster waiting to happen to the Turnkey Cleaning employees,” according to Cahanin’s lawsuit.