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AMARILLO, Texas (CBSMiami) – The deaths of four children in Texas are believed to be the result of an accidental chemical reaction involving pesticide.

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The children and six adults were inside the home when the lethal fumes seeped inside.

“The caller is saying that there are eight people sick in the house and that one is not waking up.”

Emergency responders rushed to an Amarillo house early Monday morning, unaware of what they’d be walking into.

“They thought they were just responding to a medical call,” said Capt. Larry Davis. “They found a lot of sick people. They found one child that was already unconscious and unresponsive. They pulled that child out of the house, started doing CPR. Rescue efforts were unsuccessful.”

7-year-old Felipe Balderas died at the house. 17-year-old Yasmeen Balderas, along with 11-year-old Josue Balderas and 9-year-old Johnnie Balderas were pronounced dead at the hospital.

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Six other family members, including the children’s mother and father, were also taken to the hospital.

According to the Amarillo Fire Department, a family member tried washing a pesticide containing aluminum phosphide from underneath the house.

Aluminum phosphide is a strong chemical typically used to kill insects and rodents. When combined with water, it produces a highly poisonous gas that can cause respiratory failure.

Fire Lt. Josh Whitney said the pesticide was used Sunday afternoon and leeched into the home overnight.

“The chemical is sold to only people that have a license. If you’re gonna apply chemicals to your house, you know, have somebody that’s certified to put these chemicals down,” said Whitney.

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The Amarillo Police Department is investigating, but officials say so far there’s nothing to suggest this was anything more than a terrible accident.