BEECH GROVE, Ind. (WISH) — Seven people were taken to a hospital Wednesday after a carbon monoxide leak at a tool-and-die maker on Marion County’s southwest side.

Jim Pierce, operations chief with Beech Grove Fire Department, said crews were called about 4:15 p.m. on a report of high levels of carbon monoxide at ELMCO Engineering, 6107 Churchman Road Bypass. That’s near Interstate 465 and South Arlington Avenue.

As fire crews helped plant personnel complete an evacuation, the incident was upgraded to a mass casualty event as multiple people complained of headaches and dizziness.

Pierce said the carbon monoxide leaked from a propane-powered machine in the plant. The carbon monoxide began to subside once the machine was turned off, and fire crews began to help plant personnel air out the facility.

The fire department operation chief said the injuries were minor. He expected the plant would be open for normal operations on Thursday.