Eight ADM personnel were taken to hospital via ambulance, with the extent of their injuries unknown at the time, fire department official Dan Kline said in an emailed statement, adding that the fire that was now under control.
ADM said the incident happened at 7:11 p.m. CDT (0011 GMT) and that the injured had been taken to a hospital.
The company said it did not have a confirmed cause of the incident as of Sunday night.
Comment: Footage of the explosion:
The Decatur site, ADM's North American headquarters and its largest facility globally, houses a soybean crushing plant and one of the largest corn wet mills in the world.
It also has the capacity to produce 375 million gallons of ethanol biofuel annually, making it the largest in the country, according to the Renewable Fuels Association.
It was not immediately clear whether the blast would impact the processing facilities. The company did not immediately respond to a request for further comment.