ZALESKI, Ohio (BNO NEWS) — Four people were injured after an explosion rocked a powder plant in southern Ohio on Tuesday morning, officials told BNO News.

The explosion happened just before 10.30 a.m. local time at the Austin Powder Company in the city of Zaleski, the Vinton County Sheriff’s Office confirmed. The first 911 call came in at 10.29 a.m. from a resident who heard the explosion. About a minute later, the plant called 911 to request assistance from emergency services.

The calls prompted a major emergency response and, according to the Sheriff, four people were injured in the incident. A medical helicopter transported one of the victims to a local hospital in unknown condition. Officials described it as a “trauma patient.”

The conditions of the other three victims were not immediately known.