Federal safety investigators in Nebraska are looking into structural problems as one of the likely contributors to an industrial building collapse in Omaha, Nebraska, which claimed the lives of two workers and injured a further 17.

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 a disastrous accident at the International Nutrition plant.

The accident saw the roof and third floor of the facility, which produced nutritional products for livestock and poultry feed, partially collapse onto the second floor.

“The building looked as if it had been ravaged by an earthquake,” said Battalion Chief Brad Thavenet part of the rescue team.

Thavenet said an on-site structural engineer helped rescue crews identify which areas were safe to walk on, adding that the engineer was integral to the rescue effort. Lumber was bound together and placed under unstable concrete areas to provide temporary columns.

The Battalion Chief speculates that the floors collapsed simultaneously, leaving little time for plant workers to escape unless they were extremely fortunate.

Some witnesses reported hearing an explosion, which may have been caused by combustible dust left over from the production process. This led to key structural supports failing in the fire, and the second and third floors of the plant collapsing.

Others have suggested, however that the sound and fire, which left a number of workers with burns, resulted from the collapse itself.

Occupational Safety and Health Administration (OHSA) inspectors will now try to establish a timeline for the accident, with up to six months to conclude their investigation.

OSHA spokesman Scott Allen said it may take that long to investigate “because of the complexity of the accident.”

Jay Davis, superintendent of building and development for the city of Omaha, said the structure appears to be too damaged to repair and will likely need to be razed.

“Most likely, repair at this point seems to be impractical, but the owner has indicated he will have a private structural engineer look at it,” he said.