Two Kansas companies were indicted Wednesday on federal charges of safety violations that caused a toxic chlorine gas cloud to form over Atchison in 2016.

Midwest Grain Products Inc., of Atchison, and Harcros Chemicals Inc., of Kansas City, Kan., were charged with violating the Clean Air Act and putting the public in danger.

The indictment alleges the greenish-yellow toxic chlorine gas cloud that formed over Atchison in October 2016 caused more than 140 people to seek medical attention, according to a news release from U.S. Attorney for Kansas Stephen McAllister.

The incident occurred on Oct. 21, 2016, when a Harcros driver pulled a truck into a Midwest Grain facility in Atchison to deliver sulfuric acid, according to the indictment.

An operator for Midwest Grain helped the driver access the transfer equipment, and the driver mistakenly connected the sulfuric acid line to the sodium hypochlorite line, forming a toxic gas.

The indictment said the men violated safety rules by failing to verify the connection was correct and failing to monitor the transfer.

The indictment alleges that more than 140 people had to seek medical attention after 4,000 gallons of sulfuric acid combined with 5,800 gallons of sodium hypochlorite to form the toxic cloud, which lasted 45 minutes.

The indictment said five residents were hospitalized because of exposure to the toxic gas.

McAllister said the cloud lasted until emergency personnel were able to shut off the flow.

According to Topeka Capital-Journal archives, the toxic cloud formed about 9 a.m. Atchison residents noticed a strong odor and started experiencing respiratory issues.

The two companies are charged with one count of violation of the Clean Air Act's general duty cause, which carries a fine up to $500,000; one count of knowingly releasing a hazardous pollutant, which carries a fine up to $1 million; and an alternative to count two, negligently releasing a hazardous pollutant, with a fine up to $200,000.

A web page, phone line and email address have been set up for victims to provide and get information regarding the case.

Victims can get more information on US v. Midwest Grain Products Inc. by visiting www.justice.gov/usao-ks/victim-witness and filling out a victim questionnaire; leaving a message on a designated phone line at (913) 551-6543; or emailing questions to usaks.victim.witness@usdoj.gov.