OMAHA, Neb. (AP) -- Overloaded storage bins on the roof of an Omaha livestock feed manufacturer's plant caused the building collapse that killed two people in January, federal investigators said Monday.
International Nutrition was cited for 13 violations of safety and health rules by the Occupational Safety and Health Administration. Regulators also proposed $120,560 in penalties, and they want to impose strict oversight on the company.
OSHA said nine storage bins on the plant's roof were overloaded, and the additional weight caused three floors to collapse inward in about 30 seconds. The company made nutritional products that are added to livestock and poultry feed. One of the ingredients stored in the rooftop bins was limestone.
International Nutrition officials said in a statement that they strongly disagree with OSHA's conclusions, and they denied knowing of anything that might have contributed to the collapse beforehand.
The Jan. 20 collapse killed 47-year-old David Ball and 53-year-old Keith Everett. Several others were injured. Four workers were trapped in the rubble after the collapse and had to be rescued by firefighters.
"Families lost loved ones because International Nutrition did not follow the basic safety procedures that would have prevented this senseless loss of life," said David Michaels, assistant secretary of labor for Occupational Safety and Health.
International Nutrition laid off its 25 production workers after the building collapse and outsourced its production to other companies. But officials said they were planning to rebuild the manufacturing plant in Omaha.
Investigators said the overloaded bins on the manufacturing plant's roof showed the company's disregard for employee safety. International Nutrition also received a repeat violation for allowing workers to use compressed air at more than 30 pounds per square inch.
Many of the other cited violations were related to combustible dust hazards and failure to follow respiratory protection standards.
International Nutrition has 15 days to appeal OSHA's findings and ask for the case to be reviewed.
OSHA spokesman Scott Allen said investigators haven't decided whether to recommend that local prosecutors file criminal charges in the case.
OSHA records show that International Nutrition was assessed more than $13,000 in penalties for a 2002 accident that killed a 45-year-old worker. The worker died when he fell into a moving mixer that he was cleaning.
The plant also was cited for six safety violations in 2012, ranging from a lack of facilities to flush dangerous chemicals from workers' eyes and skin to concerns over lacking safeguards for some equipment.