A tractor was towing a pair of 2-ton tanks of anhydrous ammonia in Beach Park, Ill., around 4:30am Thursday, and somehow the chemical spilled—creating a toxic plume over the area and sending 37 people to the hospital. At least seven of those people are in critical condition with life-threatening injuries, WGN-TV reports. The injured include 11 firefighters, one of whom is in critical condition, and three police officers, all of whom were treated and released. Anhydrous ammonia, which is used as a fertilizer and industrial refrigerant, can be fatal if inhaled at high concentrations. It can also cause eye, nose, and throat irritation; chest pain; pulmonary swelling; breathing difficulties; and burns, blisters, or frostbite. One woman described driving through the toxic cloud and having to pull over, "spitting up and coughing" and struggling to breathe, to call 911.
The Lake County Sheriff's Office is still investigating what happened and why the chemical was being transported in the dark, but they don't believe a traffic collision was involved, per the Chicago Tribune. Three people were found unconscious at the scene and a warning was issued just before 5am that anyone within a one-mile radius of the spill should stay inside with windows closed and heating/air conditioning systems turned off. The shelter in place order was lifted by 11am and officials say the spill has been cleaned up, though they were still waiting for the plume to dissipate and schools in the area were to be closed all day. Air quality is being tested to make sure it is safe. Most of the injuries involved breathing problems, and authorities went door-to-door to make sure everyone within a quarter-mile of the scene was OK. (A bear-spray incident sent 24 Amazon workers to the hospital.)