It happened just before 8:30 a.m. at, located on County Road E. The company produces containerboard and corrugated packaging.

A human resources manager with PCA tells us the men were burned by fly ash, a product produced during combustion of coal. Currently, they do not know exactly what happened. They say the injured parties were contractors, not employees of PCA.

A spokesperson from OSHA says they'll send an investigator to the scene to find out what went wrong.

"What they're looking to see is if there are any health and safety violations that may have contributed to the incident or may still be a danger to workers on the scene," Rhonda Burke said.

OSHA has up to six months to complete its investigation including, including surveying the area and interviewing other employees.

"If the investigator determines there were health or safety violations the company can be issued citations for those violations," Burke said. "And those citations may carry monetary penalties."

Tuesday's incident is a scary flashback to 2008. On July 29, 2008, 56-year-old Randy Hoegger of Tomahawk, 46-year-old Donald Snyder of Merrill and 52-year-old Steven Voermans of Tomahawk were killed when sparks ignited flammable gas in a storage tank at the company.