AMARILLO, Texas -- We've learned lack of education on how to use the chemical compound led to the deaths of four Amarillo children.

Aluminum Phosphide is often used as a fumigant to get rid of pests like gophers and mice. It is highly toxic to not only those animals, but humans as well.

When Aluminum Phosphide is mixed with water or any moisture, it produces a toxic Phosphine gas, which is what took the lives of these occupants. One resident of the east Amarillo home was trying to kill mice and placed the pesticide underneath their home, then applied water.

"They were already getting an odor and they were trying to suppress the vapors. He didn't know enough about the chemical," said Amarillo Fire Department Lieutenant Josh Whitney. "The chemical is only sold to people that have a license to apply it, and he got this black market. He applied it yesterday, and then so over the night is whenever all the toxic gasses were leeching to inside the house "

Aluminum Phosphide is so strong it is commonly referred to as a "restricted use" pesticide. Whitney tells us when inhaled, it attacks the respiratory system. And if someone is lucky enough to survive inhalation, they will likely experience long term health issues.

"IDLH is 50 parts per million, which 50 parts per million means it only takes 50 drops in a room full of a million to be able to become toxic and kill you. So this is extremely, extremely toxic," said Whitney.

WFAA's sister station KFDA drove around to try and find pesticides even close to these levels and...no luck. Many mice and gopher killers are now made with natural ingredients.

Whitney has some words of advice for anyone considering killing any pests.

"This is known, this happens across the United States and it's when people get a hold of stuff they don't know how to use and they don't do enough research. If you're going to apply chemicals to your house, have somebody that's certified put these chemicals down and don't put your family in harms way."