The U.S. Occupational Safety and Health Administration has cited an Omaha, Nebraska-based railcar cleaning services company for egregious health and safety violations related to a deadly blast that killed two employees in April.

Nebraska Railcar Cleaning Services is facing $963,000 in total penalties after the employees, ages 41and 45, died in the explosion, according to an agency news release issued Thursday. The explosion trapped one of the workers in the railcar while the other employee was hurled off the top of the railcar and a third employee was injured, the agency stated.

The employees were sent into the railcar, even though a check of the air quality inside indicated a serious risk of an explosion and without monitoring the air continuously for explosive hazards as required or providing the employees with emergency retrieval equipment or properly fitted respirators, according to OSHA

OSHA issued citations on Tuesday for seven egregious willful violations involving multiple instances of failing to monitor air quality properly in confined spaces as required and for not fit-testing employees required to use respirators in railcars, according to the agency's statement. Most railcars are confined spaces large enough for workers to enter and perform certain jobs such as cleaning and maintenance, but not designed for continuous occupancy. Fit testing ensures the respirators protect the employees by properly fitting their faces and preventing inhalation of hazard substances.

Safety regulations require that employers evaluate confined spaces for air quality and other hazards prior to allowing workers to enter and then monitor conditions while employees are inside, the agency stated.

Nebraska Railcar, which specializes in cleaning railcars that contained food-grade products, herbicides, pesticides, fertilizers, used oil, asphalt, gasoline and ethanol, was also cited for three willful, two repeated, 20 serious and one other than serious safety and health violations, according to the agency.

OSHA placed the company in its Severe Violator Enforcement Program, which focuses resources on inspecting employers who, according to the agency, have demonstrated indifference to their Occupational Safety and Health Act obligations through willful, repeated or failure-to-abate violations.

“This company has regularly failed to use appropriate equipment and procedures to keep their employees safe and in this case it had tragic consequences,” Jeff Funke, OSHA's area director in Omaha said in the statement. “The company needs to immediately re-evaluate its procedures for entering and cleaning railcars.”

“This isn't the first time this employer put its workers' lives at risk, but OSHA will do everything in our power to ensure it is the last,” David Michaels, assistant secretary of labor for occupational safety and health in Washington, said in the statement.

Nebraska Railcar has had five whistleblower complaints filed with OSHA since 2013, with two under investigation, two dismissed for lack of merit and one settled and subject to a non-disclosure agreement, according to the agency.

National Railcar is “very disappointed" with OSHA's handling of this investigation” and adamantly denies the company intentionally put its employees in harm's way, it stated in a press release. The alleged violations, along with incidents referenced in OSHA's 2013 investigation into the company, “have no causal connection to the explosion,” National Railcar said in the release.

The company is continuing its internal investigation into the tragic accident, according to the release. “NRCS is determined to get to the root cause of this accident because the families and the employees of NRCS have a right to know,” the company said. “NRCS will vigorously defend against these allegations because the facts simply do not support them.”

The company's workers compensation provider is Travelers Indemnity Co. of Overland Park, Kansas, according to OSHA.