Four children are dead and six other people injured after the unlicensed use of a powerful pesticide on a home in Amarillo.

As reported by Amarillo.com, investigators determined that a family member attempted to fumigate the home with a pesticide containing aluminum phosphide. They then tried to dilute or wash away the chemical using water, which caused a chemical reaction resulting in the creation of lethal phosphine gas.

“It’s a very lethal chemical,” Amarillo Fire Department Captain Larry Davis told Amarillo.com. “It causes pulmonary edema, and basically the lungs fill up with fluid. We don’t know that that’s the cause of death so far, but that’s one of the more severe symptoms. It took us a long time to identify the chemicals.”

Police, medics, and firefighters were called to the home around 5AM Monday, and at first believed they were dealing with a case of carbon monoxide poisoning.

When they arrived, they found 7-year-old Felipe Balderas lying unresponsive. He passed away at the scene. Three of his siblings - 17-year-old Yasmeen, 11-year-old Josue, and 9-year-old Johnnie - were taken to a nearby hospital where they later passed away.

Six other people exposed to the gas in the home were in stable condition Tuesday. Authorities say it is unclear how long the family was exposed to the gas.

CNN reported Tuesday that the man who sprayed the chemical on the ground around the home lived there, and got the pesticide from a friend. The EPA classifies aluminum phosphate as a Category 1 Toxin, and only licensed users are supposed to have access to it.

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