HARLAN, Iowa (AP) — A hazardous materials incident at Farm Service Co-op in western Iowa has injured two workers, who were sent to an Omaha, Nebraska hospital for treatment.

The incident happened Friday in Harlan, Iowa.

Harlan Fire Lt. Jason Wickiver says the employees were working on a semi tanker believed to contain anhydrous ammonia Friday morning when they were injured. Details of how they were injured have not been released, but exposure to anhydrous ammonia — used by farmers as fertilizer — can burn the eyes, throat and damage lung tissue.

Ron Kinkel with Farm Service Co-op said the workers were taken to Shelby County Hospital and then flown by medical helicopter to the Nebraska Medical Center.

Their names and conditions have not been released.