MADISON TOWNSHIP, OH (FOX19) - The origin of Tuesday's fire at Mar-Flex Waterproofing Products remains under investigation.
As of early Wednesday morning, investigators still had not been able to safely enter the structure. Most of the fire was out by late Tuesday night, but there were still hotspots throughout the building.
Flames broke out at the Mar-Flex Company, located at 6866 Chrisman Lane in Madison Township, a little after 1 a.m. Tuesday morning.
Fire crews said putting water on the fire could spread toxins into the ground, so they decided to let it burn itself out.
The EPA has tested the air and smoke near the fire and found that it does not contain harmful chemicals. However, the EPA warns that smoke itself can be irritating to the lungs of some people.
Officials with the Butler County Emergency Management Agency were asking about 2,000 nearby residents to stay indoors so they would not breathe the fumes. That shelter-in-place was lifted at 11 a.m. Tuesday.
Emergency officials are urging residents who experience respiratory problems or eye irritants because of the smoke cloud to call 911.
The warehouse is about the size of a football field. Mar-Flex is a waterproofing and concrete building company that uses several chemicals in their products. A spokesman for the company, Robert Hoffman, said the building is a total loss and they are working with their customers to get them what they need.