Multiple fatalities have been confirmed following a crash involving a semi-truck that leaked anhydrous ammonia in Effingham County, Illinois, authorities say.

Parts of Teutopolis were evacuated "due to the plume from the ammonia leak" after the crash Friday night on US Highway 40, about a half mile east of Teutopolis, Illinois State Police said.

Emergency crews were still on scene and working to contain the leak Saturday morning, State Police Chief Public Information Officer Melaney Arnold said in an email.

Just before 5 p.m. a separate crash had taken place on Interstate 70 just east of Effingham, which caused traffic to be rerouted to US Highway 40.

At about 9:25 p.m., ISP was notified about a crash on the highway "involving multiple vehicles, including a semi-truck that is leaking anhydrous ammonia," police said.

Those within an estimated 1-mile radius of the crash, including northeastern parts of Teutopolis, were then evacuated, police said.

The evacuation orders continued early Saturday, and a shelter was set up for those affected.

Anhydrous ammonia "is essentially pure (over 99 percent) ammonia," according to the Occupational Safety and Health Administration. " 'Anhydrous' is a Greek word meaning 'without water;' therefore, anhydrous ammonia in ammonia without water."

Ammonia used in households is a diluted water solution that contains 5 to 10 percent ammonia, according to OSHA.

Ammonia in high levels can irritate and burn the skin, mouth, throat, lungs and eyes, according to the Centers for Disease Control and Prevention. Very high levels can also damage the lungs or cause death.

Symptoms of anhydrous ammonia exposure include breathing difficulty; irritation of the eyes, nose or throat; and burns or blisters.

Effingham County has an estimated population of about 34,000 according to the US Census Bureau, and is located about two hours south of Illinois's capital, Springfield.