OMAHA, Neb. (AP) — Federal investigators say an Omaha rail car cleaning company blatantly ignored warning signs of an explosion when it sent into a rail car two employees who were killed in a blast.

Two workers, Dallas Foulk and Adrian LaPour, died in the April 14 explosion. A third employee was injured.

The Occupational Safety and Health Administration said in a release Wednesday that before the blast, a check of the air quality inside the car indicated serious risk of an explosion. OSHA says that despite the warning, the company sent Foulk and LaPour into the car to work without continuously monitoring for explosive hazards, as required, or providing the employees with safety equipment.

OSHA has cited Nebraska Railcar Cleaning Services for 33 violations. The company now faces penalties of $963,000.