CANTON -- The hazards that causedthousands of people to be evacuated Monday in Cantonwere known to federal investigatorsyears ago.

Convoy Containers, once billed as a modern 55,000 square foot plant is now smouldering rubble.

Investigators saysulfur dioxide wasthe dangerous chemical burning inside the former plant overnight Monday.

Records from the U.S. Occupational Health and Safety Administration, or OSHA. show the industrial packaging company was cited for "serious" violations months before it closed its doors 2011.

An inspection in August 2010 revealed risks, such as explosive concentrations of hydrogen sulfide gas above liquid sulfur in dip tanks, with no means to detect levels, or protect employees from an explosion that could cause death or serious physical harm.

Convoy Containers was fined$13,200 before an informal settlement for compliance was reached in early 2011.

WKYC found the former company's website lists products like a "high sulfur content paper," which itsays was"french fried" in a hot chemical strengthening solution.

"You can never, never underestimate any type of situations where chemicals are involved," said Larry Gray, a spokesperson for Cleveland Fire Department.

The Cleveland Fire Department says just like Akron, Canton and other fire districts, it completes an annual inspection on high hazard businesses so crews can know before they arrive just what's inside.

Every business is inspected at least once every two years.The inspections are the department's way of learning what types of materials they have on site, so that if there was a fire they have specific knowledge of what they are dealing with.

Companies are also required to file Material Safety Data Sheets for informational purposes. These sheets help break down what's inside a business so crews can beware.

"You always want to be aware of what different products you have and what locations they are at," said Gray. "Every station has a list of buildings that they're responsible for."

That list protects firefighters and the community.Fire Department inspectors get the EPA, even the courts, involved to help remove dangerous or abandoned or unknown chemicals.

But at times it's a costly and dangerous process.

"We're going to make all the necessary steps we have to, to make sure that if there is a problem, they clean it up," said Gray. "And that they take care and make sure the residents in that community will be safe."