The explosion took place on Monday morning in the plant under Chemtool Inc., a company that produces lubricants, grease products and other fluids, near Rockton, Winnebago County, some 152 km northwest of Chicago, Xinhua news agency reported.
“I would like to reiterate and remind the public that the evacuation order up to one mile is still in effect,” Rockton Fire Protection District Chief Kirk Wilson said at a news conference on Wednesday.
“At this point in time, I’m happy to report that there has not been any release of any toxins into our waterways and, and into our water system within the village of Rockton,” he added.
The Chemtool factory’s 70 employees were evacuated without injury.
Two firefighters were taken to hospitals, one for a minor injury to his leg and the other evaluated for smoke inhalation and has been released, local media reported.
Wilson said that fire suppression efforts were still underway.
It is expected that the fire may burn for several days.
More than 30 air quality monitors have been erected around the area.
It remains unknown when residents who evacuated will be allowed to return to their homes.