CLINTON, Iowa — We have more insight into what went wrong at Clinton’s ADM plant when an explosion killed a local firefighter and critically injured another.

Local 4 News tracked down the investigation file from the Occupational Safety and Health Administration. It turns out the fire had been burning for days.

Last month we reported OSHA fined ADM and another company involved at the plant for the deadly accident. Both companies had to pay more than $60,000 combined.

To understand the events leading up to the ADM explosion in January, you have to go back even further to last October. Documents from OSHA’s investigation reveal that’s when ADM found a blockage in grain bin number two.

The report indicates ADM brought in two outside companies to clear it. Bill Whitters Construction was one of them.

Workers used a high pressure water hose to break pieces loose, but three days before the explosion large chunks of the bridge fell into the bin’s funnel.

Workers noticed the material was smoldering, but documents say ADM told the crew to keep working.

Just before 6 a.m. Jan. 5, crews saw flames and called 911.

Firefighters asked several times if they could open a side hatch to reach the fire, ADM said it wasn’t safe.

Clinton firefighters ended up using a bucket truck to pour water in over the top, but because it wasn’t tall enough two fighters climbed out and carried the hose to the top

Those firefighters were Adam Cain and Eric Hosette.

Back on the ground, a new ADM incident commander took over, telling firefighters it was safe to use the side hatch.

But within seconds, the report said, the bin exploded.

Hosette fell from the bin and Cain became trapped inside.

Thirty minutes later, Whitters employers showed firefighters an observation port in the hatch and finally Cain was located and rescued.

Documents say ADM did not tell firefighters Whitters employees had been in the bin and would have firsthand knowledge of the situation.