(KAIR)--An Atchison company has pleaded guilty to violating the federal Clean Air Act and is expected to pay a $1 million fine.

U.S. Attorney Stephen McAllister, in a news release, said MGP Ingredients pleaded guilty Monday to a misdemeanor offense of negligently violating the Clean Air Act.

In its plea, the release says the company admitted that on Oct. 21, 2016, a greenish-yellow chlorine gas cloud formed over the city of Atchison when 4,000 gallons of sulfuric acid were mistakenly combined with 5,800 gallons of sodium hypochlorite.

The Atchison County Department of Emergency Management ordered community members to shelter in place and to evacuate in some areas. About 140 people sought medical attention. 

A federal report blamed the leak on missing key rings on chemical storage tanks and a lack of attention to procedure.

Sentencing is set for Feb. 24. The company could be sentenced to a term of probation up to five years.