OMAHA, Neb. (AP) - Federal safety investigators are looking at structural problems and a dust explosion as possible causes of an industrial building collapse in Omaha that killed two workers and injured 17 others, a federal official said Wednesday.
Inspectors with the U.S. Occupational Safety and Health Administration are working with structural engineers and combustible dust experts as part of their investigation into Monday's accident at the International Nutrition building, OSHA spokesman Scott Allen said. The plant makes nutritional products that are added to livestock and poultry feed.
Some witnesses reported hearing an explosion before the building's top two floors collapsed into the first floor. But others have suggested that the sound and fire, which burned some workers, resulted from the collapse.
Combustible dust is the technical term for any dust that will catch fire, and most dust will if it's ground finely enough. That includes dust from chemicals, plastics, metals and foods.
The material that International Nutrition worked with "can produce a dust," Allen said. "I don't have all the specifics or details ... about what products those would be, whether it's grain dust or something else."
The accident happened Monday morning while 38 workers were in or around the building. Most managed to escape, though two were killed and 10 were taken to hospitals.
The two workers killed in the collapse _ 53-year-old Keith Everett and 47-year-old David Ball, both of Omaha _ were trapped in the rubble. Firefighters were able to retrieve Everett's body Monday evening, but it took a special urban search and rescue team nearly eight hours to recover Ball's body from the collapsed building on Tuesday.
Allen stressed that it would likely be weeks before investigators know what caused the accident. The agency has six months to wrap up its investigation, he said.
OSHA investigators were able to enter the heavily-damage building Tuesday with the urban search and rescue team, Allen said.
"They've been able to recover some evidence and take some pictures of the inside," Allen said, but he declined to say what the evidence included or what the photos showed.
Allen did not know when investigators would be able to re-enter the building to continue their investigation. City officials have declared the building unsafe to enter.
A public relations firm hired by International Nutrition said company officials would not speak to reporters, but the firm did release a statement from company president Steven Silver expressing sympathy for the families of those killed and injured in the accident.
"Many of our employees have worked with us for more than 10 years, and in a family-owned business like ours, the developments that have taken place over the last day are difficult for all involved," Silver said in the written release. "In our more than 35 years of doing business, this is the most serious incident to ever happen at our operation, and we are fully cooperating with all government investigators to find the cause."
Silver said he and others will assess the damage over the coming days and "explore alternate methods of meeting our customers' needs."
The building appears to be too damaged to repair and will likely need to be razed, said Jay Davis, superintendent of building and development for the city of Omaha.
"Most likely, repair at this point seems to be impractical," he said, "but the owner has indicated he will have a private structural engineer look at it."
(Copyright 2014 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.)