The U.S. Chemical Safety Board (CSB) is investigating the chemical release Friday in Atchison, Kansas that forced thousands of residents to shelter in place and caused at least 85 people to seek medical attention for respiratory problems.

The release occurred near an onsite wastewater treatment plant owned and operated by MGP Ingredients, which produces distilled spirits and specialty wheat proteins and starches. 

It occurred when two chemicals were inadvertently mixed together and sent a thick gaseous plume into the air.

Atchison is located in northeast Kansas, about 20 miles from Leavenworth and 40 miles from Kansas City.

CSB Chairperson Vanessa Allen Sutherland said, “This incident underscores the very serious consequences that can occur when a chemical release goes beyond a facility’s fence line and impacts nearby residents.” 

The CSB is an independent federal agency charged with investigating industrial chemical accidents.