An investigation into the crash of a truck that killed five people and injured seven others, is ongoing. The crash occurred Saturday, September 30. The incident caused a toxic chemical leak as the tanker truck was carrying anhydrous ammonia. After the wreck, the tank was drained and moved to a more secure location. The National Transportation Safety Board is investigating. The tanker truck spilled its load on a highway east of Teutopolis, Illinois, Effingham County Coroner Kim Rhodes said in a statement Sunday evening. “Preliminary investigation indicates five individuals died from exposure to anhydrous ammonia at the crash site,” according to Rhodes’ statement. Anhydrous ammonia is a clear, colorless gas that is toxic. Effects of inhalation range from nausea to respiratory tract irritation, depending on the length of exposure, according to the Center for Disease Control. About 500 residents living within roughly two square miles of the crash site were initially evacuated, authorities said.