EFFINGHAM, IL – A semi-truck accident in Illinois resulted in the release of thousands of gallons of anhydrous ammonia, leading to the death of five people and the evacuation of a local neighborhood. The truck was transporting approximately 7,500 gallons of the hazardous substance when it crashed in Effingham County, according to the Illinois Environmental Protection Agency (EPA).

The EPA reported that early estimates suggest around 4,000 gallons of the toxic chemical were discharged in the incident. The leak has been partially contained, and about 500 residents have been evacuated from the surrounding area. The accident also resulted in multiple injuries in addition to the fatalities.

The crash occurred on US Highway 40, near the village of Teutopolis in south-central Illinois. The area was evacuated due to the toxic plume from the ammonia leak. Emergency crews were still working to fully contain the leak as of Saturday afternoon.

The incident was further complicated by a separate crash on Interstate 70, east of Effingham, which caused traffic to be rerouted to US Highway 40. Authorities were alerted to the multi-vehicle crash, which included the ammonia-leaking semi-truck, around 9:25 p.m. local time.

Effingham County Sheriff Paul Kuhns described the situation as large and complex. Five people were airlifted to local hospitals, according to Teutopolis Fire Chief Tim McMahon. Crews worked overnight to patch part of the rupture on the semi-truck, slowing the leak but not completely stopping it.

Residents within an estimated one-mile radius of the crash, including parts of Teutopolis, were evacuated. The evacuation orders continued into Saturday, with a shelter established for those affected. There is currently no timeline for when residents will be able to return home.

Anhydrous ammonia is a highly concentrated form of ammonia, with a purity of over 99 percent, according to the Occupational Safety and Health Administration (OSHA). In contrast, household ammonia is a diluted water solution containing 5 to 10 percent ammonia. High levels of ammonia can cause irritation and burns to the skin, mouth, throat, lungs, and eyes, and can even be fatal.

Symptoms of anhydrous ammonia exposure include breathing difficulty, irritation of the eyes, nose, or throat, and burns or blisters. The substance can enter airways and attach to mucus and moist surfaces, creating hazardous air conditions.

Effingham County, home to an estimated 34,000 residents, is located about two hours south of Illinois’ capital, Springfield.