An explosion fatally injured a worker Friday morning at the W.R. Meadows Inc. chemical plant in Hampshire, IL.

Crews were sent to the Industrial Drive facility at 10:45 a.m. and arrived on scene to find significant damage to the structure.

“There were two employees in that portion of the building when the explosion occurred, one patient was extricated and was pronounced deceased,” Hampshire Fire Protection District Fire Chief Trevor Herrmann said in a release posted to the district’s Facebook page.

Chief Herrmann told the Associated Press that the two workers were cleaning a tank when the blast occurred. The official said it is unclear what chemicals were involved.

The other injured worker was taken to an area hospital for treatment. Hampshire Fire said the worker was in critical condition. No one else was injured during the incident.

“Investigation determined that it was an accidental explosion that was caused from an electrical event in an explosive vapor atmosphere,” Chief Herrmann said.

The US Department of Labor’s Occupational Safety and Health Administration (OSHA) and the Illinois State Fire Marshal have opened investigations into the explosion.

W.R. Meadows is a manufacturer of concrete construction products.