WAUKGAN, Ill. (AP) – Prosecutors in northern Illinois say they won’t file criminal charges in connection with an April anhydrous ammonia leak that sickened more than 40 people, including first responders.

The (Waukegan) News-Sun reports that the Lake County State’s Attorney Michael Nerheim says his office has determined that no laws were broken in the April 25 incident. Federal officials determined open valves on farm fertilizer tanks led the chemical to leak in Beach Park, about 40 miles (65 kilometers) north of downtown Chicago.

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Firefighters responded to an chemical spill after a tractor hauling tanks of ammonia crashed in Beach Park on April 25, 2019. (Credit: CBS)

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Authorities have said a tractor driver was towing tanks of anhydrous ammonia from Pleasant Prairie, Wisconsin, to an Illinois farm when the chemical leaked, creating a toxic gas cloud.

Nerheim says “while the conduct of the worker may have been negligent, it didn’t rise to the level of criminal conduct.”

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